Effect of nootropic dipeptide noopept on CA1 pyramidal neurons involves α7AChRs on interneurons in hippocampal slices from rat.

Noopept (NP) is a proline-containing dipeptide with nootropic and neuroprotective properties. We have previously shown that NP significantly increased the frequency of spontaneous IPSCs in hippocampal CA1 pyramidal cells mediated by the activation of inhibitory interneurons in stratum radiatum. The cholinergic system plays an important role in the performance of cognitive functions, furthermore multiple behavioral and clinical facts link NP with the cholinergic system. The present study was undertaken to reveal the possible interaction of NP with neuronal nicotinic acetylcholine receptors (nAChRs). Currents were recorded from rat hippocampal neurons using the whole-cell, patch-clamp technique. NP (5 µM) increased the action potential firing frequency recorded from GABAergic interneurons in the stratum radiatum (SR) of CA1 region. This effect was almost completely abolished by the application of the α7 nAChR-selective antagonists α-bungarotoxin (α-BGT; 6 nM) and methyllycaconitine (MLA; 20 nM). The increase in the frequency of spontaneous IPSCs in CA1 pyramidal cells induced by NP was also eliminated by α7 nAChRs antagonists. These results imply the involvement of α7 nAChRs in the modulation of hippocampal neuronal activity caused by NP and indicate that a7 nAChRs are an important site of action of NP.