Introduction: Despite existing therapies, the neural control of breathing (nCOB) is poorly regulated, necessitating high levels of oxygen therapy (hyperoxia, HX) in premature infants. Though vital, HX facilitates chronic lung disease (bronchopulmonary dysplasia; BPD). More than 40% of BPD infants require sustained HX due to poor nCOB, for unknown reasons. This knowledge gap precludes improving breathing to reduce HX use and, therefore, BPD. Infants succumbing to BPD have alveolar loss and hyperplastic clusters of chemosensitive pulmonary neuroendocrine cells (neuroepithelial bodies, NEBs), both of which are uniquely innervated by distinct subpopulations of pulmonary vagal sensory neurons (PSNs). Herein, we sought to determine the roles of alveolar-innervating Npy2r+ and NEB-innervating Agtr1a+ PSNs on the nCOB in health and BPD-like lung disease in mice. Methods: From birth to postnatal day (P) 5, Npy2r- (n=5-8) and Agtr1a-Cre+ (n=2-13) mice were subjected to chronic neonatal HX (90% O 2 ) or room air (NX). At P5 and P7, mice were intratracheally treated with a retrograde, Cre-dependent AAV to drive expression of the synthetic, excitatory hM3Dq DREADD receptor in only lung-innervating Npy2r+ or Agtr1a+ PSNs. Then, between 4 and 6 weeks of life, room air (RA) breathing (1-3 hours) and the acute hypoxic ventilatory response (HVR; RA/O 2 ventilation x 100%) to 12% O 2 (10 minutes) were measured before and after IP injection of the DREADD activator, DCZ. Results: Lung tissue collected from subsets of mice confirmed alveolar simplification and NEB hyperplasia in HX vs NX mice (P< 0.05). RNA Scope of vagal ganglia (n=3/group) confirmed the specificity of hM3Dq expression and that Npy2r and Agtr1a are markers of distinct PSNs. Breathing was unaffected in Cre- mice treated with rAAV and later DCZ. Though Npy2r activation reduced (P< 0.05) minute ventilation (VE) by ~50% in NX and HX mice, it was driven by tidal volume (VT) in NX mice but by breathing frequency in HX mice, suggesting HX alters Npy2r-PSN neuromodulation of breathing. No such effects on ventilation during hypoxia were observed pre- or post-DCZ in NX or HX mice. In contrast, activation of Agtr1a PSNs had no effect on ventilation in NX or HX mice. However, DCZ did increase VE during the acute hypoxic condition in both NX and HX mice. Subsequent calculation of the HVR indicate similar pre- (110%) and post-DCZ (123%) HVR values for NX mice, but a significantly higher HVR post-DCZ (166%) vs pre-DCZ (113%) in HX Agtr1a mice, suggesting potential sensitization of Agtr1a PSNs in the HVR. Conclusions: Current results suggest that Npy2r PSNs influence room air breathing whereas Agtr1a PSNs influence the HVR. Such influences appear to be chronically altered following brief neonatal HX exposure. Whether Npy2r- and Agtr1a-expressing PSNs actively contribute to the neuromodulation of breathing is being investigated with ongoing PSN inhibitory DREADD studies. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Ehlert et al. (Fri,) studied this question.