Huperzine A attenuates epileptic seizures via enhancing dCA1-projecting septal cholinergic transmission

Abstract

Cholinergic transmission, independent of classical glutamatergic and GABAergic signaling, critically plays a crucial role in epilepsy. Huperzine A (Hup A), an acetylcholinesterase (AChE) inhibitor, exerts potent anticonvulsant activity, but its mechanism of action within cholinergic circuits remains unclear. Here, we show that Hup A mitigates epileptic seizures by enhancing hippocampal dorsal CA1 (dCA1)-projecting cholinergic transmission. We found that systemic injection of Hup A not only reduces seizures in acute models, including the maximal-electroshock seizure (MES), pentylenetetrazol (PTZ), and kainic acid (KA) models but also alleviates the seizure severity in chronic epilepsy models induced by kindling and KA, indicating a broad-spectrum anti-seizure efficacy. Interestingly, using immunohistochemistry, viral tracing, and in vivo fiber photometry, we found that Hup A selectively inhibits AChE in the dCA1 rather than in other hippocampal subregions or cortex, enhancing dCA1-projecting septal cholinergic transmission. Significantly, selective ablation of septal ChAT⁺ neurons reversed the anti-seizure effects of Hup A. We further identified that α7 nicotinic acetylcholine receptors in the dCA1 region mediate the anti-seizures cholinergic circuit modulated by Hup A. Together, our results demonstrate that Hup A exerts broad-spectrum anti-seizure efficacy via modulating dCA1-projecting septal cholinergic transmission, providing potential therapeutic avenues for epilepsy through targeted cholinergic modulation.

Keywords: cholinergic circuit; epilepsy; hippocampal dorsal CA1 region; huperzine A; α7 nicotinic acetylcholine receptor.