Pituitary adenylate cyclase activating polypeptide as a novel hypophysiotropic factor in fish
Bibliographic record
Abstract
Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel member of the secretin-glucagon peptide family. In mammals, this peptide has been located in a wide range of tissues and is involved in a variety of biological functions. In lower vertebrates, especially fish, increasing evidence suggests that PACAP may function as a hypophysiotropic factor regulating pituitary hormone secretion. PACAP has been identified in the brain-pituitary axis of representative fish species. The molecular structure of fish PACAP is highly homologous to mammalian PACAP. The prepro-PACAP in fish, however, is distinct from that of mammals as it also contains the sequence of fish GHRH. In teleosts, the anterior pituitary is under direct innervation of the hypothalamus and PACAP nerve fibers have been identified in the pars distalis. Using the goldfish as a fish model, mRNA transcripts of PACAP receptors, namely the PAC1 and VPAC1 receptors, have been identified in the pituitary as well as in various brain areas. Consistent with the pituitary expression of PACAP receptors, PACAP analogs are effective in stimulating growth hormone (GH) and gonadotropin (GTH)-II secretion in the goldfish both in vivo and in vitro. The GH-releasing action of PACAP is mediated via pituitary PAC1 receptors coupled to the adenylate cyclase-cAMP-protein kinase A and phospholipase C-IP3-protein kinase C pathways. Subsequent stimulation of Ca 2+ entry through voltage-sensitive Ca 2+ channels followed by activation of Ca 2+ -calmodulin protein kinase II is likely the downstream mechanism mediating PACAP-stimulated GH release in goldfish. Although the PACAP receptor subtype(s) and the associated post-receptor signaling events responsible for PACAP-stimulated GTH-II release have not been characterized in goldfish, these findings support the hypothesis that PACAP is produced in the hypothalamus and delivered to the anterior pituitary to regulate GH and GTH-II release in fish.Key words: PACAP, VIP, PAC1 receptor, VPAC1 receptor, VPAC2 receptor, growth hormone, gonadotropin-II, cAMP, protein kinase A, protein kinase C, calcium, pituitary cells, goldfish, and teleost.
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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 | 0.000 | 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) | 0.000 | 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".