Cortisol production by interrenal cells in rainbow trout (Oncorhynchus mykiss) is stimulated by 5-HT4 receptor activation
Bibliographic record
Abstract
• Serotonin stimulates the fish stress axis but the receptors involved remain unclear. • All levels of the stress axis expressed 5htr1a , 5htr2 and 5htr4. • Serotonin injection in vivo raised circulating cortisol levels but not crf or ACTH. • Cortisol production by interrenal cells was mediated by the 5-HT 4 receptor. Although serotonin (5-HT) can stimulate the hypothalamic-pituitary-interrenal (HPI) axis in fishes, the sites of 5-HT action and the receptor subtypes involved remain unclear. Therefore, the present study identified potential sites of 5-HT action within the HPI axis of rainbow trout, Oncorhynchus mykiss , and examined which of three 5-HT receptor subtypes mediated effects of 5-HT on cortisol production. Expression of the receptors 5htr1a , 5htr2 and 5htr4 was detected at all three levels of the HPI axis, with significantly higher transcript abundance in the preoptic area (POA) of the brain than in the pituitary or head kidney. Administration of 300nmol kg −1 5-HT, but not 30nmol kg −1 , to cannulated rainbow trout significantly increased circulating cortisol. Despite this cortisol response, no specific effects of 5-HT administration on POA transcript abundance of corticotropin-releasing factor ( crf ) or circulating adrenocorticotropic hormone (ACTH) concentrations were detected. To assess the direct actions of 5-HT on cortisol production, head kidney tissue was incubated in vitro with 5-HT or selective 5-HT receptor agonists. Neither the 5-HT 1A receptor agonist 8-hydroxy-2-(di- n -propylamino)-tetralin (8-OH-DPAT) nor the 5-HT 2 receptor agonist α-methyl-5-hydroxytryptamine maleate (α −methyl 5-HT) stimulated cortisol production. However, head kidney cortisol production was significantly increased by the 5-HT 4 receptor agonist cisapride, an effect that was eliminated when tissue was incubated with a combination of cisapride and the 5-HT 4 receptor antagonist GR125487. Collectively, these data support a role for 5-HT in HPI axis activation in rainbow trout, and suggest that effects of 5-HT in the head kidney are mediated by the 5-HT 4 receptor.
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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".