The Role of Pulmonary Vagal Sensory Neurons in the Neural Control of Breathing in Chronic Lung Disease

Infants born extremely prematurely (<28 weeks gestation) are prone to develop chronic lung disease and bronchopulmonary dysplasia (BPD). BPD results from vital respiratory support, like supplemental oxygen (hyperoxia; HX). Over 40% of BPD infants require sustained HX due to poor neural control of breathing (nCOB). However, the underlying mechanisms remain poorly understood. Pulmonary vagal sensory neurons (PSNs) expressing Neuropeptide Y receptor 2 (Npy2r) innervate the alveolar regions of the lungs and express inflammatory receptors. Given the decreased alveolarization, increased presence of proinflammatory markers, and dysfunctional nCOB, which are characteristic features of infants with BPD, we hypothesize that altered Npy2r PSN function contributes to the impaired nCOB in BPD. We exposed Npy2r-Cre driver mice expressing the light-sensitive, excitatory protein Channelrhodopsin (Npy2r-ChR) to either room air (n=13) or chronic neonatal hyperoxia to induce BPD with impaired nCOB (hypoventilation), as we have previously established (n=14). Mice were anesthetized, breathing was recorded via spirometry, and the diaphragm activity was measured by EMG before, during, and after brief light-stimulation epochs (0.625 W/mm 2 ; 5ms on/45ms off for 10 sec), repeated in triplicate but averaged for statistical analyses. While Npy2r stimulation caused a modest (P>0.05) 10% reduction in breathing frequency among NX mice, it caused an exaggerated (30%) reduction among HX mice (p<0.05), which led to significant and similar reductions in minute ventilation among HX but not NX mice. Optogenetic studies demonstrate that hyperoxia animals exhibit a more exaggerated reduction in breathing frequency and minute ventilation. Diaphragm activity was reduced in comparable manners. Histological analysis and whole-body plethysmography of the animal model have validated the reduced alveolarization and hypoventilation characteristic of BPD. To validate the inhibitory effects caused by optogenetics, subsets of NX mice Npy2r Cre+ (n=4) and Cre- (n=2) were intratracheally treated with a retrograde AAV to drive Cre-dependent expression of excitatory DREADS (synthetic receptors activatable by a synthetic ligand, DCZ). Indeed, for up to 100 minutes post-DCZ, breathing frequency was reduced (20-25%), and apneas were increased (500%) relative to pre-DCZ. Effects were minimal among Cre-negative mice. RNA Scope validated the Cre-dependent expression of ChR2 or DREADDs among Npy2r neurons (n=3-5/group) These results support the novel concept that BPD-lung injury may underlie impaired nCOB through impaired Npy2r-PSN signaling. Targeting this signaling pathway may enhance our understanding of mechanisms complicating BPD and potential therapeutic strategies for improving the nCOB in BPD. Neuroscience Research Center, Imagine More Award (3311232); Advancing Healthier Wisconsin REAC Award (5520640) This abstract was presented at the American Physiology Summit 2025 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.