Basic research to achieve reconstitution of optic tract and the retinotopic projection

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The purpose of the present study is to develop new strategy for reconstitution of visual pathway, from optic nerve regrowth to formation of retinotopic map. Peripheral nerve grafting is usually carried out against, the transected stump of optic nerve to stimulate axonal regeneration of retinal ganglion cells, however, the retinotopic map is not reconstituted in mammals. In the present study, I tried to graft two pieces of peripheral nerve neuraxis into the rat eye ball. One grafting was put into the nasal sclera, and another to the temporal sclera. This "double grafting" was not succeeded because of severe tissue damage, however, some important information were piled up. Especially, peripheral nerve grafting should be penetrated at the anterior portions of the Ora serrata to avoid severe intraocular hemorrhage.From the results of DNA array and cDNA differential screening between the normal retina and the retina 1 day after axotomy in the rat, I focused BH3 only proteins and new genes. … More One of BH3-only proteins, Hrk mRNA was not detectable by RT-PCR in the normal rat retina, however, Hrk expression was induced after optic nerve transection. In situ hybridization revealed that Hrk mRNA was localized in retinal ganglion cells after axotomy. Realtime RT-PCR revealed 3 times larger expression of ARG357 mRNA in axotomized rat retina than in the intact. BimEL expression was also enhanced after axotomy. Quantitative in situ hybridization using TSA systems and quantification of fluorescent strength with the confocal microscope clearly demonstrated that stronger signals for BimEL and ARG 357 were localized in the axotomized retinal ganglion cells than the intact cells. This strategy which I developed in this study is so useful to carry out molecular approach against small amount of isolated mRNAs, like as the nasal retina when analysis of reconstitution of retinotopic map.The inductions of Hrk, BimEL and ARG357 have broken through on molecular analysis of retrograde degeneration of retinal ganglion cells after axotomy. These findings have brought a valuable improvement of strategy to promote functional recovery of visual system from severe damages. Less