Subthreshold membrane potential oscillation mediates adrenosensitivity in chronically compressed DRG neurons

    XING Junª²Ling, HU Sanª²Jue

    Institute of Neuroscience of Chinese PLA, Fourth Military Medical University, Xi¡¯an 710033, China

    ¡¾Abstract¡¿ AIM£º To investigate membrane mechanism of adrenosensitivity in a neuropathic pain model caused by chronic compression of dorsal root ganglion (DRG). METHODS: Effects of norepinephrine (NE, 10 ¦Ìmol/L) on the membrane potential of DRG Aª²neurons in rats were examined intracellularly in vitro. RESULTS: NE induced depolarization in both intact (15/22) and injured (40/45) DRG neurons. NE could induce membrane depolarization in a concentrationª²dependent manner and could be blocked by phentolamine. Following NEª²induced depolarization, a subthreshold membrane potential oscillation (SMPO) could be triggered and enhanced, and consequently repetitive firing was initiated or increased only in some injured neurons (13/45). After SMPO was selectively abolished by tetrodotoxin (1 ¦Ìmol/L), NEª²induced depolarization didn't produce repetitive firing again, even by a deep depolarization. CONCLUSION: These results strongly suggest that the triggering and enhancement of SMPO may be a critical step for mediating NEª²induced excitatory effects in the injured sensory neurons. ......