The goal remains to determine the extent to which axons of a damaged spinal cord can be induced to regenerate. The spinal cord of adult rats is crushed epidurally at T-9 in rats. Axons have been identified by immunostaining for neurofilaments. However, as in all other reported cord traumas, regardless of the method of injury used, assessment of axon regeneration has been thwarted by the inability to distinguish intact, preexisting axons from newly regenerating ones. The current collaborative finding may resolve this dilemma. E10, the mRNA expressing the embryonic form of glutamic acid decarboxylase (GAD in the cord, disappears by adult life. It is now found that E-10 is reexpressed in regenerating spinal cord. The expectation is that antibodies to the embryonic form of GAD will enable its detection in axons and thus permit distinction, for the first time, between regenerating fibers and preexisting ones. In a new series, cord-injured rats are given only the free radical suppressor, deprenyl, and permitted to survive for 1 d to 5 w after the injury. Immunohistochemical identification of the predominant cell types at different stages of wound repair is being made so that a sequence of administering cytokines and growth factors, secreted by leukocytes, can be established.
