Downregulation of Protein Kinase C Levels Leads to Inhibition of GnRH-Stimulated Gonadotropin Secretion from Dispersed Pituitary Cells of Goldfish
Notice bibliographique
Résumé
We have previously shown that the abilities of the two native goldfish GnRHs, salmon GnRH (sGnRH) and chicken GnRH II (cGnRH II), to stimulate gonadotropin (GtH) secretion and elevate intracellular Ca2+ levels are mimicked by the protein kinase C (PKC) stimulators, 1,2-dioctanoylglycerol (DiC8) and 12-O-tetradecanoyl phorbol-13-acetate (TPA). The ability of PKC inhibitors to attenuate GnRH-stimulated GtH secretion was also demonstrated. In the present study, the involvement of PKC was examined through the reduction of cellular PKC levels by prolonged preincubation of the cells with TPA (TPA desensitization). TPA pretreatment reduced the levels of PKC in fish pituitary cells as measured by immunoblotting (Western blot). Pretreatment of dispersed goldfish pituitary cells in static culture with TPA abolished the GtH responses to sGnRH, cGnRH II and ionomycin, and drastically reduced TPA-and DiC8-stimulated GtH release, but had no major effect on forskolin-induced GtH release. TPA pretreatment also reduces the cell content of GtH in goldfish pituitary cells. Interestingly, treatment with all of the pharmacological secretagogues tested led to a decrease in cellular contents of GtH, however, the two native GnRHs had no such effect. In rapid column perifusion experiments (1-min fractions), the GtH responses induced by both native GnRHs were characterized by an initial acute increase in hormone secretion followed by a ‘plateau’ phase which is smaller in magnitude relative to the initial phase. TPA pretreatment of perifused cells greatly reduced both the peak and plateau phases of sGnRH- and cGnRH II-stimulated GtH secretion; TPA-induced GtH release is also greatly attenuated. In contrast, forskolin-stimulated GtH release was enhanced by TPA desensitization. The ability of fors-kolin to stimulate GtH release at similar (in static culture) or enhanced (in column perifusion) levels following TPA desensitization, despite a reduction in cell content of GtH, strongly indicates that the reduced GtH response to sGnRH and cGnRH II following TPA pretreatment is not due to a simple reduction in the availability of releasable GtH. Additionally, the magnitude of decreases in cellular contents of GtH was not sufficient to totally account for the inhibition of GnRH action observed in the PKC-depleted cells. These results strongly suggest that PKC plays an important role in both acute and prolonged GnRH-stimulated GtH secretion in the goldfish.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».