Preparation of Adult Rat Sensory Neuron Cultures and Their Application to Growth Cone Turning Assays.

The directional trajectory of growing peripheral nerve axons in the adult impacts their successful regeneration to denervated target tissues. Misdirected axons in neuromas, injured nerve trunks, or nerves with attempted repair diminish the success of regeneration. The behavior of adult rodent peripheral sensory neurons in vitro, in turn, is helpful in predicting axonal behavior in vivo. Here, we describe the adaptation of embryonic neuron growth cone turning assays, an important technique in developmental neurobiology, to adult rat sensory neurons. With some key modifications, and selection of subtypes of neurons likely to respond to a purported growth factor, short-term responses to molecular gradients can be analyzed using routine dorsal root ganglion neuronal cell culture techniques. The caveats are that short-term turning does not necessarily reflect on the overall tropic impact of a molecule, particularly if it alters growth cones through intra-axonal translation. Similarly, to understand the trajectory of an axon, it must be in a growth mode, such as that associated with preconditioning from previous injury.