Activation of NMDA Receptors in Lumbar Spinothalamic Cells is Required for Ejaculation
Bibliographic record
Abstract
INTRODUCTION: The sexual reflex ejaculation is controlled by a spinal ejaculation generator located in the lumbosacral spinal cord. A population of spinothalamic (LSt) neurons forms a key component of this generator, as manipulations of LSt cells either block or trigger ejaculation. However, it is currently unknown which afferent signals contribute to the activation of LSt cells and ejaculation. AIM: The current study tested the hypothesis that glutamate, via activation of N-Methyl-D-aspartic acid (NMDA) receptors in LSt cells, is a key regulator of ejaculation. METHODS: Expression of phosphorylated NMDA receptor subunit 1 (NR1) was investigated following mating, or following ejaculation induced by electrical stimulation of the dorsal penile nerve (DPN) in anesthetized, spinalized male rats. Next, the effects of intraspinal delivery of NMDA receptor antagonist AP-5 on DPN stimulation-induced ejaculation were examined. Moreover, the ability of intraspinal delivery of NMDA to trigger ejaculation was examined. Finally, the site of action of NMDA was determined by studying effects of NMDA in male rats with LSt cell-specific lesions. MAIN OUTCOME MEASURES: Expression of NR1 and phosphorylated NR1 in LSt cells was analyzed. Electromyographic recordings of the bulbocavernosus muscle (BCM) were recorded in anesthetized, spinalized rats following stimulation of the DPN and delivery of AP-5 or NMDA. RESULTS: Results indicate that the NR1 receptors are activated in LSt cells following ejaculation in mating animals or induced by DPN stimulation in anesthetized, spinalized animals. Moreover, NR1 activation in LSt cells is an essential trigger for rhythmic BCM bursting, as DPN stimulation-induced reflexes were absent following administration of NMDA receptor antagonist in the L3-L4 spinal area, and were triggered by NMDA. NMDA effects were dependent on intact LSt cells and were absent in LSt-lesioned males. CONCLUSION: These results demonstrate that glutamate, via activation of NMDA receptors in LSt cells, is a key afferent signal for ejaculation.
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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) | 0.002 | 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".