Role of Endogenous Release of Norepinephrine in Muscle Spasms After Chronic Spinal Cord Injury
Bibliographic record
Abstract
The recovery of persistent inward currents (PICs) and motoneuron excitability after chronic spinal cord transection is mediated, in part, by the development of supersensitivity to residual serotonin (5HT) below the lesion. The purpose of this paper is to investigate if, like 5HT, endogenous sources of norepinephrine (NE) facilitate motoneuron PICs after chronic spinal transection. Cutaneous-evoked reflex responses in tail muscles of awake chronic spinal rats were measured after increasing presynaptic release of NE by administration of amphetamine. An increase in long-lasting reflexes, known to be mediated by the calcium component of the PIC (CaPIC), was observed even at low doses (0.1-0.2 mg/kg) of amphetamine. These findings were repeated in a reduced S2 in vitro preparation, demonstrating that the increased long-lasting reflexes by amphetamine were neural. Under intracellular voltage clamp, amphetamine application led to a large facilitation of the motoneuron CaPIC. This indicates that the increases in long-lasting reflexes induced by amphetamine in the awake animal were, in part, due to actions directly on the motoneuron. Reflex responses in acutely spinal animals were facilitated by amphetamine similar to chronic animals but only at doses that were ten times greater than that required in chronic animals (0.2 mg/kg chronic vs. 2.0 mg/kg acute), pointing to a development of supersensitivity to endogenous NE in chronic animals. In summary, the increases in long-lasting reflexes and associated motoneuron CaPICs by amphetamine are likely due to an increased release of endogenous NE, which motoneurons become supersensitive to in the chronic stages of spinal cord injury.
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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 | 0.000 |
| 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".