Androgen Receptor (AR) Expression in Astrocytes from Normal and Glaucomatous Human Optic Nerve Head (ONH)

Abstract

Abstract: : Purpose: In previous investigations we demonstrated that glaucomatous ONH astrocytes in vivo and in vitro metabolize androgens into neurosteroids by expressing higher levels of the androgen–metabolizing enzyme AKR1C2 than normal astrocytes. In this study we determined whether ONH astrocytes express androgen receptor (AR) and how they respond to androgen treatment. Methods:. Quantitative real time RT–PCR (Q–PCR) with AR specific primers and SYBRGreen was performed to compare AR mRNA expression in normal and glaucomatous ONH astrocytes. Western blot and immunostaining were used to determine AR protein level and localization in cells and tissue. Proliferation assay and Q–PCR were carried out after treatment of normal ONH astrocytes with 5α–dihydrotestosterone, 3α–androstanediol and synthetic androgen R1881. Results: We demonstrated that AR mRNA expression and AR protein level in ONH astrocytes was gender independent and significantly higher in cultured glaucomatous ONH astrocytes than in normals. In cultured ONH astrocytes AR was detected in cytoplasm and nuclei by immunostaining and astrocytes responded to androgen treatment by increasing cell proliferation and AR mRNA expression. In glaucomatous ONH tissue, immunoreactivity for AR was localized in the nuclei of reactive astrocytes in the lamina cribrosa. Conclusions: ONH astrocytes are androgen sensitive cells and can respond to androgens by genomic and non–genomic mechanisms. Glaucomatous ONH astrocytes expressed higher levels of AR both in vivo and in vitro. Nuclear localization of AR in reactive astrocytes suggests that androgens in vivo participate in astrocytes transition to the reactive phenotype and it maintenance in glaucomatous ONH.

Keywords: astrocytes: optic nerve head • gene/expression • microscopy: light/fluorescence/immunohistochemistry