Spatiotemporal localization of injury potentials in DRG neurons during vincristine-induced axonal degeneration.
The distal to proximal degeneration of axons, or "dying back" is a common pattern of neuropathology in many diseases of the PNS and CNS. A long-standing debate has centered on whether this pattern of neurodegeneration is due to an insult to the cell body or to the axon itself, although it is likely that mechanisms are different for specific disease entities. We have addressed this question in a model system of vincristine-induced axonal degeneration. Here, we created a novel experimental apparatus combining a microfluidic divider with a multielectrode array substrate to allow for independent monitoring of injury-induced electrical activity from dorsal root ganglion (DRG) cell bodies and axons while isolating them into their own culture microenvironments. At specified doses, exposure of the cell body to vincristine caused neither morphological neurodegeneration nor persistent hyperexcitability. In comparison, exposure of the distal axon to the same dose of vincristine first caused a decrease in the excitability of the axon and then axonal degeneration in a dying back pattern. Additionally, exposure of axons to vincristine caused an initial period of hyperexcitability in the cell bodies, suggesting that a signal is transmitted from the distal axon to the soma during the progression of vincristine-induced axonal degeneration. These data support the proposition that vincristine has a direct neurotoxic effect on the axon.
Ravula
Surendra K
SK
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States. skravul@sandia.gov
Wang
Min S
MS
McClain
Maxine A
MA
Asress
Seneshaw A
SA
Frazier
Bruno
B
Glass
Jonathan D
JD
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000633:toxicity; D001369:Axons / Q000187:drug effects* / Q000473:pathology; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004566:Electrodes / Q000592:standards; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D005727:Ganglia, Spinal / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000473:pathology; D009498:Neurotoxins / Q000633:toxicity; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014750:Vincristine / Q000633:toxicity*; D014855:Wallerian Degeneration / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*
D000972:Antineoplastic Agents, Phytogenic; D009498:Neurotoxins; D014750:Vincristine