Impact of Orchiectomy on Oxidative Stress-Induced Neurodegeneration in the Male Rat Retina: A Proteomic Analysis.

Elevated oxidative stress (OS) is a primary driver of ocular neurodegeneration, worsening with age-related declines in gonadal hormones. While the loss of endogenous 17β-estradiol (E2) is a recognized risk factor for retinal degeneration in females, the impact of testosterone depletion in males remains poorly understood. To address this knowledge gap, we employed mass spectrometry-based proteomics and bioinformatic pipelines to characterize retinal protein shifts triggered by orchiectomy (ORX) in the Brown Norway rat. Proteins from ORX and intact retinas were analyzed via a discovery-driven approach using nanoflow liquid chromatography-tandem mass spectrometry with data-independent acquisition. Ingenuity Pathway Analysis® of differentially expressed proteins (DEPs) revealed nearly 300 significantly regulated canonical pathways, many associated with OS, free radical detoxification, mitochondrial dysfunction and ophthalmic disease. A selected panel of DEPs was verified by protein-targeted data extraction. Notably, pathway analysis revealed the prominence of estrogen receptor signaling over androgen receptor signaling in the retina, despite the loss of male sex hormones following ORX. These findings indicate that E2-mediated pathways play a more significant role in male retinal protection than previously recognized. Our study provides the first proteomics-based evidence of the male rat retina's heightened susceptibility to ORX-associated OS, identifying potential targets for treating sex hormone deprivation-associated retinal neurodegeneration.