Geniposide Attenuates Oxygen-glucose Deprivation/Recovery-induced Retinal Ganglion Cell Injury via Akt/Nrf-2 Signaling Pathway.

ABSTRACT

BACKGROUND: Glaucoma is an eye disease. Its pathological process involves retinal ischemia-reperfusion (I/R), which causes irreversible blindness in patients. Geniposide (Gen), a bioactive iridoid glycoside extracted from the fruit of gardenia, exhibits many biological effects, such as anti-oxidative stress, anti-inflammation, anti-apoptosis, anti-endoplasmic reticulum stress, and anti-thrombotic effects. However, its therapeutic potential for the retinal I/R injury remains unclear. This study investigated the protective effect of Gen against I/R injury by inhibiting abnormal reactive oxygen species (ROS) and retinal neuron apoptosis. METHODS: We used oxygen-glucose deprivation/reoxygenation (OGD/R) to induce R28 cells to mimic the pathological process of I/R in glaucoma. We conducted CCK-8 analysis and TUNEL staining to examine cell proliferation and apoptosis in glaucoma. Western blotting was used to assay the expressions of apoptosis and Akt/Nrf-2 pathway-related proteins. RESULTS: The production of ROS was detected by using the corresponding kit. Cell viability decreased, whereas TUNEL staining-positive cells and ROS production increased after the OGD/R injury. The contents of cleaved caspase-3 and Bax/Bcl-2 increased after the OGD/R injury. Treatment with 200 µM of Gen effectively improved the cell viability and suppressed cell apoptosis and ROS production. In addition, Gen could significantly promote the activation of the Akt/Nrf-2 signaling pathway in R28 cells, which was blocked by the inhibition of Akt/Nrf-2. We in vivo verified the neuroprotective effect of Gen by establishing an acute high intraocular pressure (aHIOP) model and obtained similar results to those of the in vitro experimental results. CONCLUSION: Hence, it can be suggested that Gen provides neuroprotection against the OGD/R-induced injury of R28 cells by activating the Akt/Nrf-2 signaling pathway, which is beneficial for the clinical treatment of glaucoma.