Afferent innervation of the lower oesophageal sphincter of the cat. An HRP study.

Labeling of afferent neurons by the retrograde axonal transport of horseradish peroxidase (HRP) was performed on anaesthetized cats in order to examine the afferent innervation of the lower oesophageal sphincter (LOS), involving both the vagal and the sympathetic nerves. The labeled cells, whose fibres follow the sympathetic pathways were found in dorsal root ganglia from T1 to L2. Nerve section experiments indicated that the main pathways involved were the splanchnic nerves, as expected from classical data. Additional pathways passing through the sympathetic cardiac branch emerging from the stellate ganglion and the thoracic sympathetic branches were also evidenced. This work corroborated the electrophysiological data showing the richness of the LOS sensory vagal innervation. Nevertheless, in this case the difficulties related to the HRP technique are particularly enhanced since the abdominal sensory vagal fibres can be affected by HRP injections.