Role of Piezo2 in mechanosensation by vagal esophageal afferent fibers

The esophagus is densely innervated by extrinsic sensory afferents projected from the dorsal root and vagal ganglia capable of sensing mechanical and chemical stimuli. In particular a major subset of vagal afferents innervating the esophagus are low-threshold mechanoreceptors whose activation by esophageal stretch regulates homeostatic processes like peristalsis and upper and lower sphincter muscle movements in addition to swallowing and vomiting reflexes. Importantly, the identity of specific proteins that mediate mechanotransduction within the esophageal afferents is not known. Previous studies have identified Piezo2 as a mechanosensitive ion channel expressed in various sensory afferent subsets that is required for sensing lung and bladder inflation. Hence, we hypothesize that esophageal afferent fibers from the vagal ganglia sense mechanical distention through mechanically-gated Piezo2. Here, we used two-photon imaging of neuronal GCaMP6s fluorescence in an ex vivo vagal-esophageal preparation to measure the activation of esophageal afferents in response to pressure-evoked distension of the esophagus. For control studies, GCaMP6s was expressed from the knockin ROSA26 gene under the control of cre recombinase (B6.129S6-Gt(ROSA)26Sor-tm96(CAG-CGaMP6s)Hze), following cross with the Pirt-cre (which expresses Cre in all sensory neurons). To assess the role of Piezo2, we injected retrograde AAV (rgAAV2) vector encoding Cre recombinase with a tdTomato reporter into the esophagus of Piezo2 fl/fl mice, combined with an intranodose injection of an AAV9 vector encoding GCaMP6s Ca 2+ -indicator. Only tdTomato-expressing neurons (i.e. cre expressing) were included in the GCaMP6s analysis of the Piezo2 fl/fl mice. Our preliminary data from PIRT-GCaMP6s mice studies show that distention of the esophagus with 5, 10 and 30 mmHg caused profound Ca 2+ influx in a select population of neurons in the vagal (nodose) ganglia (118 neurons analyzed), consistent with our previous electrophysiological studies of tension mechanoreceptors. However, we saw a reduction of >85% in the Ca2 + influx in response to esophageal distention (5, 10 and 30 mmHg) in the tdTomato+ esophageal afferent population following cre-mediated knockout of the Piezo2 channel (99 neurons analyzed). Our findings support our hypothesis that Piezo2 is required for sensing mechanical distention by esophageal afferents arising from the nodose ganglia. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.