Transport and turnover of acetylcholinesterase and choline acetyltransferase in rat sciatic nerve and skeletal muscle.

Abstract

Abstract:We studied the axonal transport and turnover of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities in rat sciatic nerve and skeletal muscle. AChE activity accumulated proximal to a sciatic nerve ligation rapidly and linearly for 4‐6 h, and ChAT accumulated much more slowly, but linearly, for at least 4 days. In the nerve segment distal to a ligation, AChE activity accumulated rapidly and linearly for 3‐4 h, while no change was found for ChAT for up to 48 h. Only 13% of total AChE activity in rat sciatic nerve moved in the rapidly transported phase. The absolute rate of rapid orthograde axonal transport of AChE activity was estimated to be approximately 390 mm per day and for retrograde transport approximately 230 mm per day. ChAT transport occurred only in the orthograde direction and at a rate of approximately 1‐2 mm per day. It is suggested that previous investigations of turnover of AChE and ChAT activities in skeletal muscle over‐estimated the true rate of turnover. We estimate that the theoretical minimal rate of turnover for total AChE and ChAT activities in skeletal muscle were 200 days and 950 days, respectively.