The influence of denervation on β-amyloid protein precursor and α₁-antichymotrypsin in mouse skeletal muscle

A serpin, α₁-antichymotrypsin (α₁-ACT), and Kunitz inhibitor containing forms of the β-amyloid precursor protein (βAPP) may be important components of the balance between serine proteases and inhibitors in the nervous system. In the current report we studied whether axotomy affected the localization of βAPP and α₁-ACT in adult mouse muscle. Immunocytochemical experiments indicated that βAPP was present in normal muscle both at neuromuscular junctions and within intramuscular nerves. α₁-ACT was also present at neuromuscular junctions, on the perineurium of nerves and endothelial cell surfaces. Following axotomy, both βAPP and α₁-ACT disappeared from intramuscular nerves simultaneously. However, at the neuromuscular junction α₁-ACT decreased more rapidly with βAPP lingering before disappearing.