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Selective Increase of Tetrameric (G 4 ) Acetylcholinesterase Activity in Rat Hindlimb Skeletal Muscle Term Denervation
Author(s) -
Gregory Eugene J.,
HodgesSavola Cheryl A.,
Fernandez Hugo L.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb08532.x
Subject(s) - denervation , acetylcholinesterase , motor endplate , medicine , hindlimb , endocrinology , neuromuscular junction , acetylcholine , aché , isozyme , gene isoform , motor nerve , skeletal muscle , chemistry , sciatic nerve , cycloheximide , biology , anatomy , enzyme , biochemistry , neuroscience , protein biosynthesis , gene
Acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes in gracilis muscles from adult Sprague‐Dawley rats were studied 24–96 h after obturator nerve transection. Results show a selective denervation‐induced increase in the globular G 4 isoform, which is predominantly associated with the plasmalemma. This enzymatic increase was (a) transient occurring between 24 and 60 h) and accompanied by declines in all other identifiable AChE isoforms; (b) observed after concurrent denervation and inactivation of the enzyme with diisopropylfluorophosphate, but not following treatment with cycloheximide; and (c) more prominent in the extracellular compartment of muscle endplate regions. Aside from this transient change, G 4 activity did not fall below control levels, indicating that at least the short‐term maintenance of G 4 AChE (i.e., at both normal and temporarily elevated levels) does not critically depend on the presence of the motor nerve. In addition, this isoform's activity increases in response to perturbations of the neuromuscular system that are known to produce elevated levels of acetylcholine (ACh), such as short‐term denervation and exercise‐induced enhancement of motor activity. The present study is consistent with the hypothesis that individual AChE isoforms in gracilis muscle are subject to distinct modes of neural regulation and suggests a role for ACh in modulating the activity of G 4 AChE at the motor endplate.