Dedicated C‐fibre viscerosensory pathways to central nucleus of the amygdala

摘要

Key points class="unordered" style="list-style-type:disc" id="tjp7501-list-0001">Emotions are accompanied by concordant changes in visceral function, including cardiac output, respiration and digestion. One major forebrain integrator of emotional responses, the amygdala, is considered to rely on embedded visceral afferent information, although few details are known.In the present study, we retrogradely transported dye from the central nucleus of the amygdala (CeA) to identify CeA‐projecting nucleus of the solitary tract (NTS) neurons for synaptic characterization and compared them with unlabelled, near‐neighboor NTS neurons.Solitary tract (ST) afferents converged onto NTS‐CeA second‐order sensory neurons in greater numbers, as well as indirectly via polysynaptic pathways.Unexpectedly, all mono‐ and polysynaptic ST afferent pathways to NTS‐CeA neurons were organized exclusively as either transient receptor potential cation channel subfamily V member 1 (TRPV1)‐sensitive or TRPV1‐resistant, regardless of whether intervening neurons were excitatory or inhibitory.This strict sorting provides viscerosensory signals to CeA about visceral conditions with respect to being either ‘normal’ via A‐fibres or ‘alarm’ via TRPV1 expressing C‐fibres and, accordingly, this pathway organization probably encodes interoceptive status.