Uptake and subsequent retrograde axonal transport of nerve growth factor (NFG) are not influenced by neuronal activity

NFG is taken up by adrenergic nerve terminals by a highly efficient and selective mechanism and is subsequently transported to the perikaryon by retrograde axonal transport. Neither enhanced (cold stress) nor reduced (decentralization, ganglionic blocking agents) neuronal activity affects this mechanism. In contrast, the non-specific uptake followed by retrograde axonal transport of macromolecules, which depends on excessively high concentrations of these compounds in the vicinity of the corresponding nerve terminals, is enhanced by neuronal activity.