Nerve growth in a small applied electric field and the effects of pharmacological agents on rate and orientation

The rate of growth and orientation of embryonic Xenopus nerves exposed to pharmacological agents, to an applied electric field or to both simultaneously were studied. The adenyl cyclase activator forskolin (100 microM) induced a threefold increase in the rate of elongation, as did an electric field alone. Together, their effect in augmenting rate of growth was additive, but only at a concentration of 50 microM forskolin. The normal pattern of faster growth towards cathode than anode was not present in nerves treated with the lectin concanavalin A, which also inhibits normal turning behaviour towards the cathode. Nerve orientation towards the cathode and augmented rates of growth were found in the presence of forskolin or ganglioside GM1. It is suggested that a combined approach of drug treatment and an applied electric field may be useful in promoting nerve regeneration.