Ex Vivo Analysis of Axonal Degeneration Using Sciatic and Optic Nerve Preparations

This chapter describes techniques associated to the study of axonal degeneration in the peripheral (PNS) and central nervous system (CNS) using in vitro cultured sciatic and optic nerves from mice, a technique commonly referred to as ex vivo nerve explant analysis. Degeneration of axons in this technique is induced by axotomy (or exeresis) upon dissection of nerves from the PNS or CNS. Nerves explants can be analyzed by different techniques hours or days after in vitro culture. This model has the advantage to represent an intermediate model between in vitro and in vivo. Importantly, it allows for easy administration of drugs, electrical stimulation, and is especially suited for biochemical and morphological analysis. In addition, nerve explants can be obtained from mice of different genetic backgrounds, including knockout and transgenic animals, and allows the study of Wallerian degeneration without interference from the inflammatory reaction and macrophage infiltration that takes place after nerve injury in vivo. The protocol presented here constitutes a valuable tool to analyze in vitro the mechanisms associated to axonal degeneration and the role of Schwann cells in this process.