Sympathetic Preganglionic Neurons (SPNs): a Promising Target to Regain Cardiorespiratory Control in Spinal Cord Injured (SCI) Patients
Bibliographic record
Abstract
Background The consequences of spinal cord injuries (SCI) are massive and become more severe with higher levels of injury. Lesions located on cervical portions, specifically between C1‐C3 cause an interruption of the descending bulbospinal pathways. These pathways include a key component of the neural control of respiration, linking the brainstem breathing rhythm generator with phrenic motor neurons that activate the diaphragm. Disruption to these pathways result in respiratory muscle paresis and/or paralysis, requiring mechanical ventilation. Respiratory complications, such as pneumonia and atelectasis complicate the process of weaning patients from ventilators, contributing to patient mortality. Previous data collected in the Wilson lab demonstrated that sympathetic preganglionic neurons (SPNs) located at the thoracic spinal cord have remarkable oxygen and pressure‐sensitive capabilities. Here, we hypothesized that SPNs can stimulate phrenic motor neurons independent of the brainstem. Aim To study the novel direct influence of SPNs on the phrenic motor nucleus. Methods An in situ artificially‐perfused cervico‐thoracic rat spinal cord preparation was used to record phrenic and splanchnic nerve activity while having the cervical and thoracic spinal cord separately perfused. This approach allowed us to selectively expose the thoracic segment to acute hypoxia (30 Torr; 10 min) in order to observe if cardiorespiratory responses elicited by the SPN’s could stimulate phrenic motor neurons located at the cervical spinal cord. Additionally, we recorded the electromyography activity from the diaphragm during hypoxia and ischemia (0 mmHg; 10 min). Results The results demonstrated that stimulation of the SPNs with hypoxia evoked phrenic nerve and diaphragm activity. This indicates that even without inputs from the brainstem, SPNs are responsive to hypoxia and ischemia and might have capability to stimulate phrenic motor neurons. Conclusion The implications of these findings point to the thoracic SPNs as a unique and promising target to regain cardiorespiratory control in SCI patients. Further pharmacological investigations may reveal effective treatment strategies to improve life quality and reduce mortality of SCI patients. Support or Funding Information Alberta Innovates Health Solutions (LL), Eyes High (NB), NSERC (HY), Canadian Institute of Health Research (RW).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".