Temporal Expression of Angiogenic Factors in Granulosa and Theca Cells of Developing Porcine Preovulatory Follicles and the Potential Involvement of Angiogenin in the Luteinizing Follicle.
Notice bibliographique
Résumé
Nutritional restriction and increased catabolism during lactation in primiparous sows has been associated with changes in follicle and oocyte quality and can be detrimental to embryonic survival and development in the subsequent litter. Delaying breeding of primiparous sows until the second oestrus after weaning resulted in increased embryonic survival and litter size and greater preovulatory follicle maturity. Understanding the molecular mechanisms underlying such differences is of considerable practical significance. Our previous work failed to establish a role for the transforming growth factor β superfamily in mediating these differences in follicle maturity and embryonic survival. However, our results showed that angiogenic factors represent a large component of the factors secreted by the granulosa and theca cells. Therefore, the aims of the present study were to investigate the temporal expression of the angiogenic factors HIF1A, VEGFA, ANGPT1, ANGPT2, ANG, FLT1, KDR and TEK in the granulosa and theca cells of developing porcine follicles and to determine if they could play a role in creating the differences in preovulatory follicle characteristics and embryo survival associated with the first vs. second post-weaning oestrus in primiparous sows. Granulosa and theca cells were recovered by dissection from antral follicles (2-10 mm in diameter) obtained from first parity sows at day 1, 2 and 4 after weaning and at day 14, 16 and 20 of their subsequent estrous cycle. These time points correspond to the recruitment of a growing cohort of follicles, the mid-selection phase and the final selection of the pre-ovulatory follicle population. Oviduct and uterine samples were also collected from these animals. Plasma estrogen and progesterone analysis was used to confirm the physiological status of each animal and follicular fluid estradiol concentration in day 4 and day 20 animals was also used to determine whether preovulatory follicles had been exposed to the LH surge. Total RNA was extracted, reverse transcribed and gene expression was determined by Q- PCR. The ΔCt values were calculated using cyclophilin as the endogenous reference genes and the data were analysed using the general linear model procedure of SAS (SAS Institute Inc., Cary, NC). Changes in ANGPT1, ANGPT2 and VEGFA mRNA abundance in granulosa and theca cells suggest an involvement of these genes in the selection and maintenance of the preovulatory follicle population. HIF1A mRNA abundance positively correlated with the expression of several angiogenic genes, suggesting that regulation of this transcription factor may also be important for the development of adequate vasculature. In addition, ANG mRNA abundance was higher in the theca cells isolated during the final follicle selection phase following the preovulatory LH surge of the 2nd compared to the 1st wave of follicular development. We hypothesized that increased ANG expression leads to increased vascularity in the preovulatory follicle and in the early corpora lutea. In turn, this would lead to an earlier rise in progesterone allowing a more efficient priming of the oviduct environment thereby favouring early embryo development. Differences in ESR2 and PTGFR mRNA expression observed in the oviduct of these animals appear to support our hypothesis. In conclusion, our results clearly demonstrate the presence of a complex angiogenic system within the pig ovarian follicle that could ultimately affect embryonic survival. (poster)
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 machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».