Muscle acetylcholinesterase adapts to compensatory overload by a general increase in its molecular forms

Abstract

We have investigated the impact of compensatory overload on the content of acetylcholinesterase (AChe) molecular forms in the rat fast-twitch medial gastrocnemius (MG). Overload was induced by way of a bilateral tenotomy of the MG's functional synergists coupled to a daily walking training program (15 m/min, 30% incline, up to 60 min per session, 12-18 wks). This latter condition ensured that the MG were used on a regular basis. In comparison to control values, overloaded MG showed 25 and 19% increases (P less than 0.05) in muscle wet weight and protein concentration, respectively. The content in AChe (activity per muscle) was also increased in these MG (28%, P less than 0.05). Sedimentation analyses revealed a general elevation in the content of AChe molecular forms, with A8, G2, and G1 displaying significant changes (35-42%, P less than 0.05). In a second group of rats, daily running training (27 m/min, 30% incline, using the same timetable) was supplemented to the compensatory overload. In this group, the additional running training led to a greater hypertrophic response as attested to by increases (P less than 0.05) in the MG wet weight (41%) and protein concentration (35%) in comparison to controls. However, total AChe content of these muscles was increased to an extent similar to that observed in the MG subjected only to compensatory overload (24%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Habitual exercise plus dietary supplementation with milk fat globule membrane improves muscle function deficits via neuromuscular development in senescence-accelerated mice

“…To further understand the mechanisms underlying the adaptive response of skeletal muscles in vivo, in vitro culture systems that use mechanical stretching of cultured myotubes have been developed to mimic in vivo muscle physiology (Passey et al 2011), including neuromuscular adaptation in response to exercise (Folland and Williams 2007; Hubatsch and Jasmin 1997; Jasmin et al 1991; Sveistrup et al 1995). Accordingly, we examined the effects of MFGM-derived fractions and sphingomyelin combined with mechanical stretch (as a substitute for exercise in vivo) on the expression of several genes.Treatment of the stretched cells with MFGM, PLF, SLF, or sphingomyelin significantly increased Dok-7 gene expression compared with that in cells that received mechanical stretching alone; this was evident especially in the cells treated with SLF or sphingomyelin (Figure 5).…”

The readthrough variant of acetylcholinesterase remains very minor after heat shock, organophosphate inhibition and stress, in cell culture and in vivo

“…These diverse molecular forms have specific localizations and probably specific functions. In the muscle, the size of the T 4 ‐PRiMA pool depends on the activity of the muscle and may exert a specific adaptive function, distinct from that of collagen‐tailed forms (Jasmin and Gisiger 1990; Jasmin et al . 1991).…”

“…These diverse molecular forms have specific localizations and probably specific functions. In the muscle, the size of the T 4 -PRiMA pool depends on the activity of the muscle and may exert a specific adaptive function, distinct from that of collagen-tailed forms (Jasmin and Gisiger 1990;Jasmin et al 1991). In the brain, during early development or in the neurodegenerative Alzheimer's disease, the ratio between monomers and tetramers is higher than in normal adult brain (Atack et al 1983;Muller et al 1985) where T 4 -PRiMA is the main form in the different brain structures, cholinergic or not (Perrier et al 2003).…”

Age and activity-related changes in the respiratory motor system

“…5) 34) . In young rats, the training effects at neuromuscular junctions were introduced previously, such as an increased safety factor due to increased neurotransmitter release when given active training stimuli 35) , nerve terminal enlargement 36) , and increased acetylcholinesterase activity 37,38) . From these observations, it was thought that nerve terminal enlargement, increased acetylcholine release, and increased acetylcholinesterase activity were attributable to increased Fig.…”