The influence of supraspinal impulse activity on the intra‐axonal transport of acetylcholine, choline acetyltransferase and acetylcholinesterase in rat motor neurons

The effect of supraspinal impulse activity upon the intra-axonal transport of acetylcholine (ACh), ACh esterase (AChE) and cholineacetyltransferase (CAT) in rat sciatic nerve has been studied. A decreased inpulse activity was obtained by spinal cord transsection (SCT) in the thoracic region 18 h, 6 days or 20 days before killing the rats. An increased neuronal activity was obtained by exercising the rats in a commercial rodent treadmill a couple of hours per day for 14 days. The amounts of substances which had accumulated in the sciatic nerve segments relative to a nerve crush performed 12 or 18 h. earlier were used to calculate the intra-axonal transport. The amounts of proximo-distal transported ACh decreased markedly with time after the SCT, while the proximo-distal transport of AChE-activity increased. Physical exercise appeared to increase ACh-transport. Thus, input to motor pericarya from supraspinal centers may regulate intra-axonal transport from the cell body of motor neurons into their axons.