Ropivacaine inhibits neurite outgrowth in PC-12 cells.

Peripheral nerve injury often leads to neuropathic pain, which might involve sympathetic postganglionic nerve fiber sprouting in the dorsal root ganglion. Recent studies suggest the effectiveness of ropivacaine in blocking neuropathic pain. To determine if ropivacaine affects sympathetic sprouting, we used pheochromocytoma (PC-12) cells, which differentiate into neurons on exposure to nerve growth factor (NGF). PC-12 cells were precultured in the presence of 50 ng/mL of NGF for 4 days. Neurite outgrowth was quantified as neurite extension after 24-, 48-, and 72-h exposure to ropivacaine at doses ranging from 10 to 200 microg/mL. Ropivacaine inhibited the neurite outgrowth in a dose-dependent manner. The inhibitory effect of ropivacaine was completely reversible because the NGF-stimulated neurite outgrowth was recovered to control level after washing out ropivacaine. Ropivacaine, therefore, may exert its therapeutic action on neuropathic pain, at least in part, by suppressing sympathetic sprouting.