Abstract
Abstract: :
Purpose: The small heat shock protein Hsp27 is not normally detected in retinal ganglion cells (RGCs) of the normal adult rodent. We have recently shown that Hsp27 is expressed in a subset of RGCs following optic nerve transection. The fraction of these RGCs expressing Hsp27 increases for up to 2 weeks after injury, indicating that Hsp27 expression may be associated with RGC survival. However, the fraction of Hsp27–positive cells remains small, increasing from 1% to 10%, 3 to 14 days after injury, respectively. The purpose of this study was to determine whether successful regeneration of RGCs into a peripheral nerve graft is associated with Hsp27 expression. Methods: Adult Sprague–Dawley female rats (n=8) underwent left optic nerve transection and suturing of an autologous peroneal nerve graft to the optic nerve stump. Eight weeks later, RGCs that had successfully regenerated into the peripheral nerve graft were labeled retrogradely from the graft with Fluorogold. Animals were sacrificed and the retinas immunolabelled for Hsp27. Retinas were examined for the presence of Fluorogold–positive and Hsp27–positive cells in the retina. Results: The retinas of all eight animals showed evidence of Fluorogold–positive cells, indicating successful RGC regeneration (mean: 587 cells/retina; range: 47–1178). A surprisingly large number of these cells (32% +/– 13%) were also Hsp27–positive. Conclusions: At two months, approximately one–third of RGCs that have successfully regenerated into a peripheral nerve graft express Hsp27. This study demonstrates that regeneration of RGCs is associated with Hsp27 expression.
Keywords: ganglion cells • regeneration • stress response