Effects of a Low-protein Diet with Varying Methionine Levels During Pregnancy on Litter Size, Fetal Weight, and Amino Acid Metabolism.
Notice bibliographique
Résumé
Feeding a low-protein, casein-based, methionine (MET) supplemented diet to pregnant rats is a well-established model to study developmental programming. Currently, the mechanisms leading to these reprogramming events are unresolved; one possible explanation is that the higher supplemental MET in the low-protein diet could disrupt one-carbon (1-C) metabolism at the level of the mother, the fetus or both. Since 1-C metabolism, involving such events as nucleoside synthesis and epigenetic transfers, is especially critical during the embryonic/ fetal period of life, it seems plausible that disruption of these processes could result in the long-term reprogramming of offspring observed. We propose that a low-protein high-MET diet will disrupt 1-C metabolism in dams and/or fetuses. Phase one of this study presents plasma amino acid profiles of dams at day 20 of gestation. Wistar rats were fed ad libitum, commencing on day zero of pregnancy, one of three diets: 18% casein with 0.5% supplemental MET (18-0.5, "control"; n=6), 9% casein with either 0.5% or 1.0% supplemental MET (9-0.5; n=6 and 9-1.0; n=6, respectively). Food consumption and maternal weight gain were monitored throughout the study. On day 20 of gestation, subsequent to maternal euthanasia, fetuses were excised and weighed and litter size was assessed. Maternal and fetal plasma, livers and kidneys were collected. Plasma free amino acid profiles were determined by HPLC using the Pico-Tag method (Waters). No significant differences were observed in food consumption, maternal weight gain or litter sizes (18-0.5: 14.3±0.7; 9-0.5: 14.5±0.9; 9-1.0: 12.4±1.6 fetuses). Fetal weights were unaffected by diet. Surprisingly, levels of the toxic, non-protein, sulfur-containing amino acid homocysteine (HCY), which serves to connect the folate and MET cycles in 1-C metabolism, did not differ significantly (18-0.5: 30±8; 9-0.5: 43±11; 9-1.0: 52±6 μM). However, maternal plasma MET levels were elevated by 42% in both 9-0.5 and 9-1.0 (respectively 148±23; 149±10 μM; p<0.05) compared to the control diet (86±12). Threonine (THR), the catabolism of which can be used to increase folate supply, was decreased in 9-0.5 by 47% and by 57% in 9-1.0 (respectively 186±24; 151±19 μM; p<0.001) compared to controls (18-0.5: 355±24), but levels were not significantly different between the low-protein diets. Relative to the control group, serine (SER) and glycine (GLY), two amino acids which are catabolised in the regeneration of methylated folates, tended to be reduced in 9-1.0 (respectively p=0.06; p=0.08), with GLY tending to be further reduced in 9-1.0 relative to 9-0.5 (p=0.08). Together, these results indicate a possible disruption of 1-C metabolism, specifically at the intersection of the MET and folate cycles. Decreases in plasma THR, SER and GLY, in combination with the increased plasma MET and unaltered plasma HCY suggests usage of 5-methyl-tetrahydrofolate for HCY re-methylation. Thus, regulation of plasma levels of HCY may be achieved at the expense of creating a functional folate deficiency within dams of the 9-0.5 and 9-1.0 treatment groups. Reprogramming could result from the impaired folate status, or through interactive effects of depleted folates and reduced dietary protein. Further assessment of 1-C metabolism disruption at the fetal and maternal level is currently underway. (platform)
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 | 0,001 |
| 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 ».