The influence of skeletal muscle on the electrical excitability of dorsal root ganglion neurons in culture

• Published in: The Journal of neuroscience Vol. 7; no. 8; pp. 2412 - 2422
• Main Authors: Chen, GG, Cole, AE, MacDermott, AB, Lange, GD, Barker, JL
• Format: Journal Article
• Language: English
• Published: Washington, DC Soc Neuroscience 01-08-1987; Society for Neuroscience
• Subjects: Action Potentials; Animals; Biological and medical sciences; Cells, Cultured; Central nervous system; Cesium - pharmacology; Chlorides; Cobalt - pharmacology; Culture Media; Electrophysiology; Fetus; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - drug effects; Ganglia, Spinal - embryology; Ganglia, Spinal - physiology; Membrane Potentials; Mice; Muscles - physiology; Sodium - physiology; Tetrodotoxin - pharmacology; Time Factors; Vertebrates: nervous system and sense organs; Cell culture; Spinal cord; Conditioned medium; Rodentia; Central nervous system; Discharge pattern; Electrophysiology; Nerve growth factor; Striated muscle; Vertebrata; Unit response; Mammalia; Mouse; Spinal ganglion; Membrane potential
• ISSN: 0270-6474; 1529-2401

Dorsal root ganglion (DRG) neurons from embryonic mice grown in coculture with dissociated skeletal muscle or in skeletal muscle conditioned medium (CM) showed an increased incidence of repetitive firing of action potentials when injected with sustained (60-100 msec) depolarizing current. This is in contrast to DRG neurons grown in monoculture and normal medium, which exhibit such behavior far less frequently. The first action potential showed less sensitivity to block with TTX and more sensitivity to Ca2+ channel blockers than the subsequent action potentials. The increased incidence of repetitive firing occurred when CM was added after as few as 2 or as many as 22 d in culture and with as little as 1-7 hr exposure to CM. This effect of CM cannot be mimicked by NGF or by coculture with cells from embryonic spinal cord (Peacock et al., 1973), can be eliminated by heating the CM at 56 degrees C for 30 min, and partially reversed following short exposure to CM. These results indicate that skeletal muscle releases some heat-labile factor(s) that can cause repetitive firing and, in addition, significant decrease in input resistance in the CM-treated neurons and a depression of the anomalous rectification, neither of which could account for the increase in repetitive firing.