Glutamate-Induced Oxidative Stress and Possible 17β-Estradiol Neurotoxicity in HT22 Cells: An in vitro Study

Sammanfattning

Glutamate is an endogenous excitatory neurotransmitter. At high concentrations, it is neurotoxic and contributes to the development of certain neurodegenerative diseases, such as Alzheimer’s disease. This study focused on the sensitivity of HT22 cells, an immortalized mouse hippocampal cell line, to glutamate-induced neurotoxicity as well as the effect of concomitant treatment with N-acetyl-L-cysteine (NAC), a glutathione precursor, with particular emphasis on oxidative stress. Cell viability was measured using the AlamarBlue assay and showed that glutamate reduces viability in a concentration-dependent manner with an IC₅₀ of 1.154 mM. Combined treatment with NAC increased the IC₅₀, indicating that reactive oxygen species (ROS) accumulation is central to glutamate-induced oxidative stress and that NAC protects against glutamate-induced cell death. Nuclear morphology was assessed with Hoechst 33342 staining and ROS accumulation with DCF-DA assay, but the results deviated from previous reports and require methodological optimization. Given that chemical exposures play a significant role in neurodegeneration, we posed the question of whether 17β-estradiol has neurotoxic effects in cultured HT22 cells. 17β-estradiol exhibited neurotoxicity only at 50 µM, a high and physiologically irrelevant concentration, where the effect likely involves mechanisms beyond ROS neutralization. In conclusion, this study supported the utility of HT22 cells as a model for screening chemical compounds and their utility in investigating mechanistic pathways of neurodegeneration. This research line is important for understanding the links between chemical exposure and the pathogenesis of brain diseases, like Alzheimer’s disease.