Recently, a number of studies have shown that mammalian central nervous system axons can regrow following lesion if given the proper environment (Richardson, 1980; David and Aguayo, 1981; Bently and Aguayo, 1982; Guth et al., 1981; Silver and Ogawa, 1983; Goldberg et al., 1986). These findings have renewed interest in regeneration of central nervous system neurons with much of the attention focused on inducing regeneration in species that under normal conditions exhibit little capacity for recovery of function, e.g., rats. While these experiments have produced dramatic and exciting results, they have not revealed the requirements for, or the mechanisms of, successful regeneration. The experiments described in this proposal will provide a detailed description of naturally occurring regeneration in an adult system, the salamander spinal cord. These studies will complement the mammalian studies of regeneration and provide a basis for future studies of the molcular biology of regeneration. The salamander spinal cord has been a model system for the study of regeneration for several decades because of the salamander's ability to recover function after transection of large ablation (e.g., Piatt, 1955a,b; Holtzer, 1951; Butler and Ward, 1967; Stensaas, 1983). Despite this long history many important questions remain unanswered: 1) what percentage of cells regenerate following ablation or transaction of the spinal cord and what is the origin of these cells, 2) where are the somata that give rise to the axons found in the regenerated spinal cord and how far do regenerated axons grow pass the lesion site into the undamaged spinal cord, 3) do regenerated axons make synapses which are appropriate, and 4) how does the repopulation of the damaged spinal cord by neurons and fiber tracts relate to recovery of function. Horseradish peroxidase (HRP) pathway tracing techniques and 3H-thymidine labeling will be utilized to examine these questions in order to produce a complete description of the events involved in the regeneration of the thoracic and lumber regions of the salamander spinal cord.
| Davis, B M; Duffy, M T; Simpson Jr, S B (1989) Bulbospinal and intraspinal connections in normal and regenerated salamander spinal cord. Exp Neurol 103:41-51 |
