Effect of Angiotensin II on Bovine Follicular Growth and mRNA Encoding Steroidogenic Enzymes, Gonadotrophin Receptors, and Tissue Development Genes.
Bibliographic record
Abstract
Angiotensin II (AngII) has been shown to be involved in the regulatory mechanism of ovulation and oocyte nuclear and cytoplasmic maturation in cattle. In rats, AngII induces apoptosis in granulosa cells and atresia of antral follicles during follicular development. However, the angiotensin converting enzyme (ACE) mRNA expression increases at the end of follicular maturation, suggesting a possible modulatory role of AngII for ovulation in cows. In addition, the expression of AngII type 2 receptors (AGTR2) is higher in healthy than in atretic follicles and, in vitro, is stimulated by FSH in bovine granulosa cell culture. Based on this evidence, this study was carried out to establish the role of AngII during the follicular growth and the effect of AngII inhibition on steroid secretion and follicular cell gene expression profile. Cows were pre-synchronized to induce a new follicular wave and the largest follicle was injected with saralasin (AngII inhibitor; 10μM), AngII (10μM) or saline when it reached 7-8mm diameter. The intrafollicular injections were performed through a double-needle system and guided by a 7.5 MHz vaginal ultrasound probe. All follicles were monitored by ultrasonography for 96 hours after intrafollicular injection. Follicles injected with saline (control group) reached ovulatory size and ovulated after a challenge with the GnRH agonist gonadorelin, demonstrating that the intrafollicular injection did not affect follicular growth. Saralasin inhibited follicular growth in all treated cows (4/4), suggesting that AngII is essential for follicular growth in 7-8mm follicles. However, intrafollicular injection of AngII affected neither follicular growth nor the pattern of follicular dynamics, which were similar to control cows. These results imply that bovine ovarian follicles contain sufficient AngII for follicle development. In a second experiment, a single follicle of each cow was injected with saralasin or saline and cows were ovariectomized 24h later. The follicular fluid was aspirated to determine steroid concentrations, and granulosa and theca cells were recovered for gene expression measurement. Estradiol concentration in follicular fluid was determined by radioimmunoassay. Messenger RNA levels were analyzed by real-time RT-PCR and are expressed relative to cyclophilin. The inhibition of AngII action decreased abundance of mRNA encoding aromatase (CYP19), 3β-hydroxysteroid dehydrogenase (3β HSD), LH receptor, SerpinE2 and cyclinD2 in granulosa cells but not StAR, 17β HSD, FSH receptor, growth arrest and DNA damage inducible (GADD45b) or X-linked inhibitor of apoptosis protein (XIAP). In theca cells, the inhibition of AngII decreased the expression of AGTR2 but not the expression of steroidogenic enzymes genes. Taken together, these results show that AngII is essential for follicular growth, and plays important role in regulating genes involved in granulosa cell proliferation and differentiation, which are necessary for development of the dominant follicle. These data suggest that AngII signaling is involved in follicle growth and dominance in cattle. (poster)
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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 | 0.001 | 0.001 |
| 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".