Glucosamine and selenium differentially regulate glutathione, lipid peroxidation, and mitochondrial function during glutamate stress in retinal neural cells.

Glutamate can disrupt cystine-dependent glutathione metabolism and promote oxidative and mitochondrial dysfunction in neural cells. We integrated human multiple-sclerosis optic-chiasm transcriptomics (GSE100297), glutamate-treated primary-neuron RNA sequencing (GSE255041), R28 differential-expression summaries, a normal human optic-nerve single-nucleus atlas (GSE236566), and R28 retinal precursor-cell experiments to characterize glucosamine (GlcN) and selenium responses. Human tissue showed enriched unfolded-protein-response, oxidative-stress, apoptosis, and ferroptosis programs, whereas glutamate-treated neurons predominantly exhibited amino-acid stress, unfolded-protein response, oxidative stress, and apoptosis, with weaker concordant ferroptosis enrichment. Glutamate reduced R28 metabolic activity, GSH/GSSG, and mitochondrial respiration and increased DCFH-DA and BODIPY-C11 oxidation. GlcN (2.5 mM) shifted the glutamate dose-response curve rightward and preserved GSH/GSSG and respiration, but lowered basal metabolic activity, mitochondrial membrane potential, and ATP-based viability. GlcN increased the LC3B-II/LC3B-I ratio, while changes in PCNA-normalized NRF2-related protein signals were modest. Ferrostatin-1 (Fer-1) partially restored respiration during glutamate exposure and was associated with higher ATP-based viability. RSL3 and erastin markedly reduced viability without glutamate; Fer-1 substantially restored viability, whereas GlcN did not. Selenium (1 μM) partially reduced RSL3-associated loss of viability without glutamate; the selenium-associated viability gain diminished during glutamate co-exposure (adjusted interaction P=0.0342). Selenium showed dose-dependent effects: 1 and 5 μM preserved metabolic activity, 5 μM reduced lipid oxidation, and 20 μM increased basal lipid oxidation. GlcN increased global O-GlcNAc modification approximately 3.6-fold and altered gp130 migration. In normal human optic nerve, redox/lipid-peroxidation programs were highest in myeloid cells, whereas hexosamine/O-GlcNAc capacity and SLC7A11 expression were prominent in astrocytic-stromal compartments. These findings identify distinct functional responses to GlcN and selenium within a mixed glutamate-stress phenotype that includes a ferrostatin-sensitive component. The GPX4 dependence of GlcN-mediated protection against glutamate remains unresolved.