AXOTOMY AS AN EXPERIMENTAL-MODEL OF NEURONAL INJURY AND CELL-DEATH

Axonal transection provides very useful paradigms to study cellular re sponses to injury, mechanisms of regeneration and plasticity, and proc esses that lead to nerve cell degeneration. Moreover, models of axotom y are valuable for testing experimental therapeutic approaches. Lesion s can be made with great precision, and, depending on the neural syste m, location of the lesion, and age of the animal, these models allow t he opportunity to examine a range of neuronal responses. Many paramete rs influence the character, evolution, and outcomes of axotomy-related processes. The most severe outcome of axotomy is cell death, very com mon in lesions of neurons of the central nervous system (CNS), althoug h neurons of the peripheral nervous system (PNS) may also die if the t ransection is sufficiently close to the neuronal cell body or if lesio ns are performed in young animals. Studies of axotomy models have prov ided clues into the cellular/molecular events associated with neuronal death and the ways in which interventions can delay or prevent proces ses that lead to cell death. In this review, we select examples, prima rily from our own work, to illustrate how axotomy models have enhanced our understanding of neuronal responses to injury, clarified mechanis ms of both regeneration/plasticity and degeneration/cell death, and al lowed assessments of the utility of therapeutic approaches.