Neural induction of the 16S acetylcholinesterase in muscle cell cultures

Abstract

SEDIMENTATION analysis of rat muscle acetylcholinesterase (AChE) has revealed the existence of three molecular forms, 4S, 10S and 16S (refs 1, 2). The 16S form was exclusively found in skeletal muscle segments containing neuromuscular junctions; it disappeared after denervation^1,2 and reappeared following rein-nervation either at the original endplate, or at ectopic sites. The 16S AChE may therefore be referred to as an ‘endplate specific’ form, but it clearly does not represent all activity at the endplate. It took several days for the disappearance of the 16S form after denervation, suggesting a postsynaptic localisation². In posterior leg muscles from rat embryos, the 16S form was absent before the 14th day of gestation; it appeared at day 15 and was relatively more abundant on day 16 (25% of the total AChE activity) than in the adult (5%). (The total AChE activity increased by a factor of 10³ from day 16 of gestation to the adult muscle².) We present here some data concerning the synthesis of the 16S form by embryonic rat cells in culture, which demonstrate that this form is produced by muscle cell cultures on induction by neuronal elements.