Transport of Muscarinic Cholinergic Marker Protein Activities in Regenerating Sciatic Nerve of Rat

The transport characteristics of choline acetyltransferase (ChAT; EC 2.3.1.6), acetylcholinesterase (AChE; EC 3.1.1.7), and the muscarinic acetylcholine receptors (mAChR) were studied in perineurally sutured, regenerating rat sciatic nerve. At different times after repair, the sciatic nerve was ligated for 24 h, and the activities of the cholinergic marker proteins, as well as the binding capacity, were measured proximally and distally from the ligature. The number of bidirectionally transported receptors increased linearly up to 5 months postoperatively (6.1-33.6% and 5.6-25.6% of the control level proximal and distal to the ligature, respectively). The quantity of anterogradely transported ChAT reached a plateau 3 months postoperatively (74.9% of the control level), whereas the retrogradely transported enzyme was then only 34.7% of the control value. The activity of AChE increased linearly during nerve regeneration, and exceeded the control level after 4 months (121.0% and 63.7% proximally and distally, respectively). The data indicate that the altered bidirectional transport of cholinergic marker proteins may be monitored quantitatively during nerve regeneration. This method might be suitable for studies of the nerve regeneration process.