Structural Proteins in human and murine retina

Abstract

Purpose: This study aimed to describe the distribution of NFs and type 2 protein associated with microtubule (MAP-2) in dead-donor human retinas and to study the distribution of these proteins in a model of retrograde retinal ganglion cell (RGCs) degeneration in murine retina induced by an electrolytic lesion within the superior colliculus. Moreover, we aimed to evaluate the viability of this experimental model without the interference of an increased IOP.

Methods: To achieve this, we submitted male C57bl/6 mice to a stereotaxic surgery for superior colliculus electrolytic lesion only in the right side; therefore, the left eye was used for the experimental group and the right eye for the control group. Also, retinas of male mice that were not submitted to any procedure were used as a second control group, which was called naïve group. The groups were evaluated 7, 15 and 45 days after the superior colliculus lesion. The characterization of the NFs in the human and murine retina was obtained through immunohistochemical essays and real-time PCR; for MAP-2, only immunohistochemical essays were performed for human retina, while both techniques were performed for the murine retina.

Results: The results revealed that both NFs and MAP-2 are present in the ganglion cell M in the human retina. In the experimental animal model the immunohistochemical essays demonstrated decrease of NFs in the experimental group when compared to the naïve group, mainly after 45 days post lesion; however, MAP-2 was increased after 15 days post lesion. The real-time PCR analysis demonstrated increased NFs and decreased MAP-2 expression when compared to the naïve group. Besides, there was a decrease of the retina thickness in the experimental group in every time point analyzed. Cellular loss, however, was only observed after 45 days post lesion and this loss was more evident in peripheral retina.

Conclusions: Hence, we can conclude that there was variation of mRNA expression and structural protein levels before the loss of RGCs with experimental group retina. Lastly, the results related to NFs and MAP-2 in this experimental animal model can be extrapolated to humans, as these proteins are also present in the human RGCs that are affected early in glaucoma.