The overproduction of neurotoxic amyloid-β (Aβ) peptides in the brain is a hallmark of Alzheimer's disease (AD). To determine the role of intracellular zinc ion (iZn2+) dysregulation in mediating Aβ-related neurotoxicity, this study aimed to investigate whether N, N, N', N'‑tetrakis (2‑pyridylmethyl) ethylenediamine (TPEN), a Zn2+‑specific chelator, could attenuate Aβ25-35‑induced neurotoxicity and the underlying mechanism. We used the 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay to measure the viability of primary hippocampal neurons. We also determined intracellular Zn2+ and Ca2+ concentrations, mitochondrial and lysosomal functions, and intracellular reactive oxygen species (ROS) content in hippocampal neurons using live-cell confocal imaging. We detected L-type voltage-gated calcium channel currents (L-ICa) in hippocampal neurons using the whole‑cell patch‑clamp technique. Furthermore, we measured the mRNA expression levels of proteins related to the iZn2+ buffer system (ZnT-3, MT-3) and voltage-gated calcium channels (Cav1.2, Cav1.3) in hippocampal neurons using RT-PCR. The results showed that TPEN attenuated Aβ25-35‑induced neuronal death, relieved the Aβ25-35‑induced increase in intracellular Zn2+ and Ca2+ concentrations; reversed the Aβ25-35‑induced increase in ROS content, the Aβ25-35‑induced increase in the L-ICa peak amplitude at different membrane potentials, the Aβ25-35‑induced the dysfunction of the mitochondria and lysosomes, and the Aβ25-35‑induced decrease in ZnT-3 and MT-3 mRNA expressions; and increased the Cav1.2 mRNA expression in the hippocampal neurons. These results suggest that TPEN, the Zn2+-specific chelator, attenuated Aβ25-35‑induced neuronal damage, correlating with the recovery of intracellular Zn2+ and modulation of abnormal Ca2+-related signaling pathways.
Keywords: Aβ25–35; Calcium ions signal; Organelle damage; ROS; TPEN; Zinc ions.
© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.