Effect of age and nerve injury on cross-excitation among sensory neurons in rat dorsal root ganglia

Spike activity in dorsal root ganglion (DRG) neurons depolarizes passive ne ighbors that share the same ganglion. We asked whether age or prior nerve i njury affect this 'cross-depolarization' signal. Intracellular recordings m ade from excised DRGs in vitro revealed that the prevalence and duration of cross-depolarization were no greater in adult than in young rats, and that its amplitude was significantly smaller in adults. The amplitude of cross- depolarization was not affected by nerve injury. The decrease in membrane i nput resistance (R-in) observed during cross-depolarization was less than t hat expected from equivalent depolarization alone. This affirms prior evide nce that the neural process underlying cross-depolarization causes a net in crease in R-in. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.