Further electrophoretic studies on proteins of neuronal origins in skeletal muscle

Abstract

Previous autoradiographic evidence showed that neuronal proteins pass from the hypoglossal nerve into tongue muscles and subsequent biochemical studies indicated that axonal proteins reach the styloglossus muscle at four intervals (about Days 1, 12, 22, and 34) after their synthesis. Also, an electrophoretic analysis ( pH 8.6, 7.5% gels) characterized several neuronal proteins that reach the muscle at Day 22. In the present study, l-[ 3H]lysine was applied to the fourth ventricle of rabbits. One to seventy days later, soluble and Triton X-soluble proteins were extracted from three segments of the hypoglossal nerve and from the styloglossus muscle and were analyzed by electrophoresis at pH 4.2 using 15% gels. One radioactive soluble protein appeared in nerve and muscle only at Day 1. Others reached their highest activity simultaneously in the three nerve segments at Day 12 and then slowly entered the muscle, one peaking around Day 22, four others at Day 34. Among the Triton X-soluble proteins, some were present in the distal part of the nerve at Day 12. Others appeared in the proximal nerve segment at Day 12 and moved proximodistally, reaching the distal nerve segment between Days 34 and 45. The Triton X-soluble proteins remained confined to the nerve and showed only traces of radioactivity in the styloglossus muscle.