Changes in synaptic inputs to sympathetic preganglionic neurons after spinal cord injury
Bibliographic record
Abstract
Spinal cord injury (SCI) leads to plastic changes in organization that impact significantly on central nervous control of arterial pressure. SCI causes hypotension and autonomic dysreflexia, an episodic hypertension induced by spinal reflexes. Sympathetic preganglionic neurons (SPNs) respond to SCI by retracting and then regrowing their dendrites within 2 weeks of injury. We examined changes in synaptic input to SPNs during this time by comparing the density and amino acid content of synaptic input to choline acetyltransferase (ChAT)-immunoreactive SPNs in the eighth thoracic spinal cord segment (T8) in unoperated rats and in rats at 3 days or at 14 days after spinal cord transection at T4. Postembedding immunogold labeling demonstrated immunoreactivity for glutamate or gamma-aminobutyric acid (GABA) within presynaptic profiles. We counted the number of presynaptic inputs to measured lengths of SPN somatic and dendritic membrane and identified the amino acid in each input. We also assessed gross changes in the morphology of SPNs using retrograde labeling with cholera toxin B and light microscopy to determine the structural changes that were present at the time of evaluation of synaptic density and amino acid content. At 3 days after SCI, we found that retrogradely labeled SPNs had shrunken somata and greatly shortened dendrites. Synaptic density (inputs per 10-microm membrane) decreased on ChAT-immunoreactive somata by 34% but increased on dendrites by 66%. Almost half of the inputs to SPNs lacked amino acids. By 14 days, the density of synaptic inputs to dendrites and somata decreased by 50% and 70%, respectively, concurrent with dendrite regrowth. The proportion of glutamatergic inputs to SPNs in spinal cord-transected rats ( approximately 40%) was less than that in unoperated rats, whereas the GABAergic proportion (60-68%) increased. In summary, SPNs participate in vasomotor control after SCI despite profound denervation. An altered balance of excitatory and inhibitory inputs may explain injury-induced hypotension.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".