Modulation of Ca oscillation following ischemia and nicotinic acetylcholine receptors in primary cortical neurons by high-throughput analysis.

Calcium oscillations in primary neuronal cultures and iPSCs have been employed to investigate arrhythmogenicity and epileptogenicity in drug development. Previous studies have demonstrated that Ca influx via NMDA and nicotinic acetylcholine receptors (nAChRs) modulates Ca oscillations. Nevertheless, there has been no comprehensive investigation into the impact of ischemia or nAChR-positive allosteric modulators (PAM) drugs on Ca oscillations at a level that would facilitate high-throughput screening. We investigated the effects of ischemia and nAChR subtypes or nAChR PAM agonists on Ca oscillations in high-density 2D and 3D-sphere primary neuronal cultures using 384-well plates with FDSS-7000. Ischemia for 1 and 2 h resulted in an increase in the frequency of Ca oscillations and a decrease in their amplitude in a time-dependent manner. The NMDA and AMPA receptor inhibition significantly suppressed Ca oscillation. Inhibition of NR2A or NR2B had the opposite effect on Ca oscillations. The potentiation of ischemia-induced Ca oscillations was significantly inhibited by the NMDA receptor antagonist, MK-801, and the frequency of these oscillations was suppressed by the NR2B inhibitor, Ro-256981. In the 3D-neurosphere, the application of an α7nAChR agonist increased the frequency of Ca oscillations, whereas the activation of α4β2 had no effect. The combination of nicotine and PNU-120596 (type II PAM) affected the frequency and amplitude of Ca oscillations in a manner distinct from that of type I PAM. These systems may be useful not only for detecting epileptogenicity but also in the search for neuroprotective agents against cerebral ischemia.