Activation of Gastrin-releasing Peptide Receptors in the Lumbosacral Spinal Cord is Required for Ejaculation in Male Rats
Bibliographic record
Abstract
INTRODUCTION: Ejaculation is a complex reflex mediated by a spinal ejaculation generator located in the lumbosacral spinal cord and consisting of a population of lumbar spinothalamic (LSt) neurons. LSt neurons and their intraspinal axonal projections contain several neuropeptides, including gastrin-releasing peptide (GRP). AIM: To test the hypothesis that GRP is critically involved in mediating ejaculation by acting in autonomic and motor areas of the lumbosacral spinal cord, utilizing a physiological paradigm to investigate ejaculatory reflexes in isolation of supraspinal inputs. METHODS: Dual immunohistochemistry for GRP and galanin was performed to investigate co-expression of GRP in LSt cells of control male rats. Next, anesthetized, spinalized male rats received intrathecal infusions of either GRP antagonist RC-3095 (0, 10, or 20 nmol/10 µL) or GRP (0, 0.2, 0.5 nmol/10 µL). Ejaculatory reflexes were induced by electrical stimulation of the dorsal penile nerve (DPN) which reliably triggers rhythmic increases in seminal vesicle pressure (SVP) and contractions of the bulbocavernosus muscle (BCM), indicative of the emission and expulsion phases of ejaculation, respectively. MAIN OUTCOME MEASURES: GRP in LSt cells was expressed as percentages of co-expression. SVP and electromyographic recording (EMG) of BCM activity following drug treatment and DPN stimulation were recorded and analyzed for numbers of SVP increases, BCM events and bursts. RESULTS: GRP was exclusively expressed in LSt cells and axons. Intrathecal infusion of RC-3095, but not saline, blocked SVP increases and BCM bursting induced by DPN stimulation. Intrathecal infusions of GRP, but not saline, triggered SVP increases and BCM bursting in 43-66% of animals and facilitated SVP increases and BCM bursting induced by subthreshold DPN stimulation in all animals. CONCLUSION: These data support a critical role for GRP for control of the emission and expulsion phases of ejaculation in male rats by acting in LSt target areas in the lumbosacral spinal cord.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".