Dendritic nicotinic receptors modulate backpropagating action potentials and long‐term plasticity of interneurons

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Abstract
Stratum radiatum interneurons, unlike pyramidal cells, are rich in nicotinic acetylcholine receptors (nAChRs); however, the role of these receptors in plasticity has remained elusive. As opposed to previous physiological studies, we found that functional α7‐subunit‐containing nAChRs (α7‐nAChRs) are abundant on interneuron dendrites of rats. Moreover, dendritic Ca2+ transients induced by activation of α7‐nAChRs increase as a function of distance from soma. The activation of these extrasynaptic α7‐nAChRs by cholinergic agonists either facilitated or depressed backpropagating action potentials, depending on the timing of α7‐nAChR activation. We have previously shown that dendritic α7‐nAChRs are involved in the regulation of synaptic transmission, suggesting that α7‐nAChRs may play an important role in the regulation of the spike timing‐dependent plasticity. Here we provide evidence that long‐term potentiation is indeed boosted by stimulation of dendritic α7‐nAChRs. Our results suggest a new mechanism for a cholinergic switch in memory encoding and retrieval.