Key points are not available for this paper at this time.
Selective modifications in the expression or function of dendritic ion channels regulate the propagation of synaptic inputs and determine the intrinsic excitability of a neuron. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels open upon membrane hyperpolarization and conduct a depolarizing inward current (Ih). HCN channels are enriched in the dendrites of hippocampal pyramidal neurons where they regulate the integration of synaptic inputs. Synaptic plasticity can bidirectionally modify dendritic HCN channels in excitatory neurons depending on the strength of synaptic potentiation. In inhibitory neurons, however, the dendritic expression and modulation of HCN channels is largely unknown. In this study, we systematically compared the modulation of Ih by synaptic potentiation in hippocampal CA1 pyramidal neurons and stratum Radiatum (sRad) interneurons. Ih properties were similar in inhibitory and excitatory neurons and contributed to resting membrane potential and action potential firing. We found that in sRad interneurons, HCN channels were downregulated after synaptic plasticity, irrespective of the strength of synaptic potentiation. This suggest differential regulation of Ih in excitatory and inhibitory neurons, possibly signifying their distinct role in network activity.
Herstel et al. (Thu,) studied this question.