268 CYCLIC GUANOSINE MONOPHOSPHATE INHIBITS PHOSPHODIESTERASE 3 ACTIVITY IN PORCINE OOCYTES
Bibliographic record
Abstract
The level of cyclic adenosine monophosphate (cAMP) within oocytes has been shown to play a critical role in maintaining meiotic arrest. High levels of intracellular cAMP prevent spontaneous oocyte maturation in vitro, whereas a decrease in oocyte cAMP is associated with the resumption of meiosis. Another cyclic nucleotide that also was recently proposed as being involved in meiotic resumption is cyclic guanosine monophosphate (cGMP), which could be regulating phosphodiesterase (PDE) 3 activity. The aim of this study was to determine whether cGMP inhibits cAMP-PDE activity in porcine oocytes. With the method described previously by Sasseville et al. (2006 BMC Dev. Biol. 6, 47), PDE activity was measured in groups of 10 oocytes cultured in the absence (control) or presence of different concentrations of cGMP (1, 3, 10, 30, 100, 300, 1000, and 3000 nM) or with the PDE3 inhibitor cilostamide (10 µM). Before assaying PDE activity, the cumulus–oocyte complexes (COC) were matured in vitro for 24 h in the presence of pregnant mare serum gonadotropin (5 IU) and hCG (5 IU) at 38.5°C in 5% CO2. The COC were homogenised in a hypotonic buffer. Data were analysed using one-way ANOVA followed by Duncan’s post-hoc test. Differences with P < 0.05 were considered significant. Results showed that 300, 1000, and 3000 nM cGMP inhibited PDE3 activity (7.9, 5.1, and 4.1 fmol min–1 per COC; P < 0.05) at levels below the controls (13.2 fmol min–1 per COC) and were similar to the activity observed in the presence of (2.4 fmol min–1 per COC; P > 0.05). The other concentrations tested were similar to activity levels seen in the control (1 to 100 nM; 12.2, 11.3, 10.8, 11.5, and 10.4; P > 0.05). In conclusion, the results support the concept that increasing concentrations of cGMP inhibit PDE activity, suggesting the inhibition of the predominant form of cAMP-PDE present in porcine oocytes, PDE3. These results support the hypothesis that cGMP inhibits PDE activity in porcine oocytes. Further work is needed to determine the role this plays in maintaining high cAMP levels and inhibiting oocyte nuclear maturation. Financial support from FGZ FAPESP 2010/20188-6 and 2010/18023-9 is acknowledged.
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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 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".