M(?)ller Cell-neuron Interactions During Laser Induced Retinal Injury

ObjectiveTo study the role of Miiller cells during laser-induced retinal photoreceptor degeneration, we start with distributed disciplinarian and effect of the low-affinity neurotrophin receptor p75 (p75NTR) and TrkA in laser induced retinal injury. On the basis of NGF can bind two distinct receptors: TrkA and p75NTR of Miiller cells, to detect products o f its intrinsic b asic fibroblast growth factor (bFGF), and to further discuss Miiller glia -neuron cell interactions. They provide academic and laboratorial evidences for molecular pathological mechanism and new therapeutic target during laser injuried retina.MethodsThe rats were anesthetized and exposed to frequency doubling Nd:YAG( . =532nm) laser for 100 plus per eye. Firstly, we detected protein and mRNA distribution of TrkA and p75NTR by immunohistochemistry and in situ hybridization in injuried retina during the 12h, 24h, 3d, 7d, 14d and 28d following laser exposure , and laser-induced photoreceptor apoptosis by TUNEL staining. Secondly, we observed expression of intrinsic bFGF after NGF 20ul (0.03ug/ul) was injected into the rat vitreous using a microsyringe by immunohistochemistry and Western Blot analysis after laser exposure, and using hematoxylin and eosin staining and visual electrophsiological instrument in order to study bFGF direct action on photoreceptors from structure and function.ResultsImmunohistochemistry and in situ hybridization results showed a differential distribution for these two neurotrophin receptors in the laser injuried retina. TrkA was enhanced in nerve fiber layer (NFL) , ganglion cell layer(GCL) and inner nuclear layer(INL) ,which is the most nuclei of the ganglion cells, proximal Muller cell end feet and a little cells in the innermost part of the INL, its peak of up-regulation was after day 1-3 , after day 28 there was sustained, whereas p75NTR expression was enhanced in the outer nuclear layer(ONL), which is distal Muller cell processes , p75NTR up-regulated after 24 hours, its peak was on day 3 , on day 14-28 there was sustained in the GCL, which is proximal Muller cell processes.TUNEL staining result found photoreceptor apoptosis was accorded with distribution and expressed peak of the specific p75NTR proteins after laser injuried retina early.From the result of immunohitochernitry and Western Blot analysis, we can find that bFGF protein of injection NGF after 72 hours is lower than that of control after laser exposure (P<0.01) .The result showed that extrinsic NGF modulated the products ofbFGF.The morphologic study showed NGF group was significantly worse than the control groups after laser exposure. From the result of electroretinogram (ERG) we can find that the b-wave and OPs-wave amplitudes recovery of NGF group were lower than the other controls after laser exposure.ConclusionsOur studies showed that Miiller-photoreceptor cells network structure is important role in laser injuried retina, we suggest the interactive structure as new therapeutic targets after laser exposure.