Expression of TRPV1 channels by Cajal‐Retzius cells and layer‐specific modulation of synaptic transmission by capsaicin in the mouse hippocampus

Key points By taking advantage of calcium imaging and electrophysiology, we provide direct pharmacological evidence for the functional expression of TRPV1 channels in hippocampal Cajal‐Retzius cells. Application of the TRPV1 activator capsaicin powerfully enhances spontaneous synaptic transmission in the hippocampal layers that are innervated by the axons of Cajal‐Retzius cells. Capsaicin‐triggered calcium responses and membrane currents in Cajal‐Retzius cells, as well as layer‐specific modulation of spontaneous synaptic transmission, are absent when the drug is applied to slices prepared from TRPV1−/− animals. We discuss the implications of the functional expression of TRPV1 channels in Cajal‐Retzius cells and of the observed TRPV1‐dependent layer‐specific modulation of synaptic transmission for physiological and pathological network processing.