Grape Pomace and Resveratrol Do Not Restore Glucose Tolerance in the Ovariectomized Rat
Bibliographic record
Abstract
Objective The loss of estrogen in females is associated with a worsening of insulin sensitivity. Natural compounds such as resveratrol (RESV) have potential insulin sensitizing effects. Grape pomace (GP) is a byproduct of winemaking, and contains RESV and other antioxidants. To our knowledge, the efficacy of RESV and GP in restoring glucose tolerance in ovariectomized (OVX) rats has not been explored. Methods Phyto‐estrogen free diet was administered ad libitum to sham control (SHAM, n=10) and OVX (n=40) female Sprague‐Dawley rats for 12 wks until the onset of glucose intolerance in OVX rats. Glucose tolerance was assessed with an intraperitoneal glucose tolerance test (IPGTT; 0.5g glucose/kg body mass) over a 2 hr period. Following the induction of glucose intolerance, OVX animals were divided into treatment and control groups (n=10 each). The first treatment group received a daily physiological dose of estrogen (E2, 28μg/kg body mass) orally via a Nutella cream (5μL sesame oil/1g Nutella/kg body mass). Another group of rats received a daily dose of RESV (5mg/kg body mass) mixed into the Nutella cream. Finally, the last treatment group had GP supplemented at 1.5% of their diet which provides about 5mg/kg body mass of RESV per day. SHAM, OVX CON, and OVX GP each received a daily dose of untreated Nutella. Animals were allowed ad libitum access to food, and treatment continued for 6 wks. At the end of the treatment period, IPGTTs were performed as well as an intraperitoneal insulin tolerance test (IPTT). 2–3 d after the TTs, terminal surgeries were performed during which muscle red (RG) and white gastrocnemius (WG) muscles and subcutaneous and visceral adipose tissue was harvested before and 10 min after insulin injection (1 μg/kg body mass). Liver was sampled post insulin injection. All tissues were stored at −80°C. Tissues were analyzed for insulin signaling (phospho‐AktSer473). Visceral adipose was preserved and stained for analysis of adipocyte size. Results OVX animals were significantly heavier than control animals at the onset of glucose intolerance and this did not change throughout the treatment period. OVX animals consumed significantly more food during the first 6 wks following ovariectomy. OVX rats were glucose intolerant compared to SHAM controls after 12 wks (area under the curve (AUC): SHAM=316 vs OVX=CON 506 mM × min, p=0.0002,); none of the treatments restored normal glucose tolerance during the subsequent 6 wks (AUC OVX CON=452, E2=493, RESV=404, GP=453 vs SHAM=223 mM × min, p=.0121). Insulin tolerance was not worsened in OVX rats, and was unaffected with treatment. No difference in liver pAkt content was found between SHAM and OVX animals (p=0.3599). A significant increase was detected in pAkt in insulin simulated RG muscle compared to basal (p<0.0001); however there was no effect of ovariectomy (p=0.3680), and the interaction was not significant (p=0.3660). Similarly, pAkt content was increased in insulin stimulated WG muscle (p<0.0001), but there was no effect of ovariectomy (p=0.7822) or interaction (p=0.8037). Adipocyte size was significantly increased in the E2 (p=0.0552) and RESV (p=0.0121) groups compared to SHAM. Conclusion RESV and GP were not effective in restoring normal glucose tolerance in OVX rats. Support or Funding Information Ontario Ministry of Agriculture, Food, and Rural AffairsNatural Sciences and Engineering Research Council of Canada
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".