4-(1-Methylethoxy)- N -(2-methyl-8-quinolinyl)-benzamide (CDN1163) Attenuates Glutamate-Induced Excitotoxicity by Suppressing ER Stress and Restoring Mitochondrial Dynamics in N2a Cells

Excessive glutamate release during excitotoxic events such as stroke and neurodegeneration leads to elevated mitochondrial reactive oxygen species (ROS) production and mitochondrial membrane depolarization, contributing to dysfunction of the sarco/endoplasmic reticulum Ca 2 + -ATPase (SERCA) and subsequent endoplasmic reticulum (ER) stress. SERCA is critical for maintaining ER Ca 2 + homeostasis, and its impairment exacerbates ER stress and neuronal excitotoxicity. In this study, we investigated the neuroprotective potential of CDN1163 (4-(1-methylethoxy)- N -(2-methyl-8-quinolinyl)-benzamide), a small-molecule SERCA activator, in an in vitro model of glutamate-induced toxicity using N2a cells. Glutamate exposure markedly reduced cell viability and induced apoptosis, as evidenced by increased caspase-3 and Bax expression along with suppression of the antiapoptotic protein Bcl-2. These cytotoxic effects were accompanied by excessive intracellular and mitochondrial ROS generation and dissipation of the mitochondrial membrane potential (ΔΨ m ), indicating mitochondrial dysfunction. Glutamate further disrupted mitochondrial quality control by impairing mitophagy initiation, reflected by reduced PINK1 and Parkin expression and altered LC3-II and phospho-p62 levels. This mitochondrial impairment coincided with pronounced ER stress, characterized by activation of unfolded protein response signaling pathways, including increased expression of BiP, p-IRE1α, XBP 1s, p-PERK, p-eIF2α, ATF4, CHOP, and ATF6, together with downregulation of SERCA1a and SERCA2b, leading to ER Ca 2 + dyshomeostasis. Treatment with CDN1163 significantly reversed glutamate-induced cytotoxicity by restoring cell viability, suppressing apoptosis, reducing mitochondrial and cellular ROS, stabilizing mitochondrial membrane potential, reactivating mitophagy, and alleviating ER stress through restoration of SERCA expression and ER Ca 2 + homeostasis. Collectively, these findings demonstrate that CDN1163 confers neuroprotection against glutamate-induced excitotoxic injury by targeting interconnected mitochondrial and ER stress pathways, highlighting its therapeutic potential in excitotoxic neurodegenerative conditions.