Paeoniflorin Protects Retinal Ganglion Cells in Experimental Glaucoma

Glaucoma is a progressive neurodegenerative eye disease characterized by raised intraocular pressure and a loss of retinal ganglion cells, resulting in partial or total vision loss. We have investigated whether paeoniflorin could reduce intraocular pressure and improve retinal ganglion cell survival in glaucoma-induced rats. In rats with raised intraocular pressure induced by injecting hypertonic saline solution into the limbal veins, oral paeoniflorin markedly brought down the elevated intraocular pressure and significantly prevented retinal ganglion cell loss, as determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay and Fluoro-Gold labeling. The expression of the transforming growth factor β protein was effectively diminished by paeoniflorin administration. Also, the expression of extracellular matrix components matrix metalloproteinase 9 a tissue inhibitor of metalloproteinase 1—laminin, collagen I, and collagen IV in the optic nerve head and retinal ganglion cell layer were effectively diminished. Paeoniflorin substantially upregulated the activation of Janus kinase-2/signal transducer and activator of transcription proteins-3 signaling, which plays a crucial role in retinal ganglion cell survival. These results illustrate a protective effect of paeoniflorin through reduction of intraocular pressure, retinal ganglion cell loss, and changes in the extracellular matrix by regulating transforming growth factor β2 signaling and Janus kinase-2/signal transducer and activator of transcription protein-3 signaling. The present work demonstrates that paeoniflorin may be a promising therapeutic agent for glaucoma.