Dissociated Hippocampal Neurons Exhibit Distinct Zn²⁺ Dynamics in a Stimulation-Method-Dependent Manner

Ionic Zn²⁺ has increasingly been recognized as an important neurotransmitter and signaling ion in glutamatergic neuron pathways. Intracellular Zn²⁺ transiently increases as a result of neuronal excitation, and this Zn²⁺ signal is essential for neuron plasticity, but the source and regulation of the signal is still unclear. In this study, we rigorously quantified Zn²⁺, Ca²⁺, and pH dynamics in dissociated mouse hippocampal neurons stimulated with bath application of high KCl or glutamate. While both stimulation methods yielded Zn²⁺ signals, Ca²⁺ influx, and acidification, glutamate stimulation induced more sustained high intracellular Ca²⁺ and a larger increase in intracellular Zn²⁺. However, the stimulation-induced pH change was similar between conditions, indicating that a different cellular change is responsible for the stimulation-dependent difference in Zn²⁺ signal. This work provides the first robust quantification of Zn²⁺ dynamics in neurons using different methods of stimulation.