The absence of NIPA2 enhances neural excitability through BK (big potassium) channels

To reveal the pathogenesis and find the precision treatment for the childhood absence epilepsy (CAE) patients with NIPA2 mutations.

We performed whole-cell patch-clamp recordings to measure the electrophysiological properties of layer V neocortical somatosensory pyramidal neurons in wild-type (WT) and NIPA2-knockout mice.

We identified that layer V neocortical somatosensory pyramidal neurons isolated from the NIPA2-knockout mice displayed higher frequency of spontaneous and evoked action potential, broader half-width of evoked action potential, and smaller currents of BK channels than those from the WT mice. NS11021, a specific BK channel opener, reduced neuronal excitability in the NIPA2-knockout mice. Paxilline, a selective BK channel blocker, treated WT neurons and could simulate the situation of NIPA2-knockout group, thereby suggesting that the absence of NIPA2 enhanced the excitability of neocortical somatosensory pyramidal neurons by decreasing the currents of BK channels. Zonisamide, an anti-epilepsy drug, reduced action potential firing in NIPA2-knockout mice through increasing BK channel currents.

The results indicate that the absence of NIPA2 enhances neural excitability through BK channels. Zonisamide is probably a potential treatment for NIPA2 mutation-induced epilepsy, which may provide a basis for the development of new treatment strategies for epilepsy.