Effects of energy deprivation on Wallerian degeneration in isolated segments of rat peripheral nerve

An acceleration in the progression of Wallerian degeneration was demonstrated in isolated segments of rat peripheral nerve following incubation under energy-deprivational conditions. The additions of1mM cyanide, azide or dinitrophenol to Ringer's incubational solutions brought about granular disintegrative axoplasmic changes, varicosity formation and linear fragmentation of the myelinated nerve fibers within 2–4 h of incubation at 37°C. Incubations in Ringer's solutions without glucose or with the addition of1mM iodoacetate led to identical Wallerian-like degenerative changes of myelinated fibers during the 8–12 h incubational interval. In contrast, the myelinated nerve fibers remained well-preserved following 16 h of incubation in glucose-enriched Ringer's solutions. The progressions of degenerative changes under energy-deprivational conditions were calcium-dependent as evidenced by their failure to occur in calcium-free media. Accordingly, it is believed that an influx of calcium ions into axoplasm is a critical event in bringing about accelerated as well as the natural degradative changes within isolated nerve fibers. It would follow that the maintenance of axolemmal integrity, especially the calcium-excluding mechanism(s), is an active process which utilizes energy and is vulnerable to energy-deprivational conditions.