The Effects Of Ciliary Neurotrophic Factor On The Regeneration Of The Optic Nerve In Rats

Objective To observe the effectiveness of Oil in labeling RGCs and its normal value by retrograde labeling bilateral superior colliculi(SC); To investigate the effects of CNTF on the regeneration of the optic nerve by observing the RGCs axon regeneration after using CNTF or other factors.Methods In the first part, using stereotactic injection method, we applied the fluorescent stain Oil to bilateral superior colliculus (SC) in 18 normal SD rats, and counted the RGCs after different periods of 3 days,7 days, 14 days and 30 days of retrograde labeling. In the second part, after the right optic nerve was transected intraorbitally, the self optic nerve or the sciatic nerve graft was sutured to theaxotomized optic nerve, furthermore,2 1 BSS or CNTF was injected immediately intothe vitreous body after the peripheral nerve was transplanted. Animals were allowed to survived 3 days, 7 days and 14 days. Regenerating RGCs were labeled by the dye Dil to the distal end of the transplanted nerve 3 days before the animals were killed. Results1. 3 days after Dil was injected into the bilateral SC, the red RGCs were seen in the retina, which increased with the labeling time. The Dil-labeled cell densities were 140423/mm2 642 51/mm2,1757 70/mm2 and 1602 56/mm2 respectively 3 days 7 days 14 days and 30 days later. There were significant difference between the adjacent groups (P<0.01) .2. There were only one Dil-labled cell was seen in one rat in the self-aastomosis group 14 days later.3. There wrere no significant Dil-labeled cells in optic nerve-sciatic nerveaastomosis 3 days after the operation. However, the cell densities were 152 26/mm2 and 297 31/mm2 7 days and 14 days later, which were significantly higher than those of theself-aastomosis group of the same period (P < 0.01) .4. There wrere no significant Dil-labeled cells 3 days after BSS was injected into the vitreous body after the sciatic nerve was transplanted. However, the cell densitieswere 260 40/mm2 and 350 52/mm2 7 days and 14 days later. There were significant difference comparing with the optic nerve-sciatic nerve aastomosis group 7 days later(P< 0.01) , but no significant difference 14 days later (P > 0.05) .5. There were no significant Dil-labeled cells 3 days after CNTF was injected into the vitreous body after the sciatic nerve was transplanted. However, the cell densitieswere 446 49/mm 2 and 560 74/mm 2 7 days and 14 days later, which were all significantly higher than those of the optic nerve-sciatic nerve aastomosis group of the same period (P < 0.01) .Conclusions1. Dil is a useful label for specific studies of RGCs. The cell densities accounted 14days after the Dil application would be the normal RGCs density, that is 1757 70/mm2. After the optic nerve is transected and the self optic nerve is transplanted, individual RGCs might regenerate and pass the injury site, but the weak regeneration is senseless to the construction of the ocular function.3. After the optic nerve is transected and the sciatic nerve is transplanted, the sciatic nerve might promote the optic nerve regeneration by providing suitable micro-circumference.4. After the sciatic nerve is transplanted and the foreign CNTF is used, the RGCs are observed to regenerate significantly, and the effect exists 2 weeks later.