Effects of Age and Long-Term Ovariectomy on the Estrogen-Receptor Containing Subpopulations of Beta-Endorphin-Immunoreactive Neurons in the Arcuate Nucleus of Female C57BL/6J Mice
Notice bibliographique
Résumé
We have reported a decrease in the number of arcuate nucleus (ARC)-immunoreactive β-endorphin neurons in old (24 months) female C57BL/6J mice versus young (5 months) mice. Here, we have tested by immunocytochemistry whether age-related changes in β-endorphin neuron numbers are selective for β-endorphin neurons which do or do not contain estrogen receptors (E2R). We also compared β-endorphin neuron number in mice with short- (S) and long-duration (L) ovariectomy (OVX), since the latter may protect against neuroendocrine aging. Mice were studied at 5 (young), 12 (middle-aged), or 23-24 months (old). When the mean number of neurons per tissue section (15 sections per animal) was examined, there were no significant differences between young and middle-aged S-OVX females for either β-endorphin, E2R, or β-endorphin/ E2R neuron number. However, there were significant decreases in β-endorphin-containing neurons in the oldest age group versus young females (young S-OVX: 74.4 ± 11 (±SD) immunopositive neurons per tissue section, n = 10 mice; young L-OVX: 61.6 ± 6.9, n = 6; old S-OVX: 45.7 ± 9.9, n = 7; and old L-OVX: 37.5 ± 7.3, n = 7). There were also decreases in β-endorphin neurons which contained E2R in the oldest animals (young S-OVX: 16.6 ± 6.4; young L-OVX: 13.7 ± 1.3; old S-OVX: 9.2 ± 1.8; L-OVX: 6.0 ± 1.5) (p < 0.05 ANOVA). Both age (p < 0.001, two-way ANOVA) and ovarian status (p < 0.05) independently affected neuron number for both the β-endorphin and β-endorphin E2R populations versus young mice. We tested whether the observed age and/or ovarian-related decreases were proportionally greater in the subpopulation of β-endorphin neurons which contained E2R compared to the total β-endorphin neuron population. In the oldest age group, there was no significant difference in the decrease with age in the population of β-endorphin neurons which contained E2R and the total β-endorphin population (p = 0.208). When we examined the E2R neuron population as compared to the β-endorphin neuron populations, age-related decreases in the β-endorphin neuronal population tended to be greater than the decreases seen in the E2R neuron population (p = 0.054 repeated measures ANOVA). The tyrosine hydroxylase (TH) neuron population was studied to test whether there were changes in another ARC neuron population. There was no age-related change in either TH neuron number (young S-OVX: 35.8 ± 6.2, n = 4; middle-aged S-OVX: 33.1 ± 2.8, n = 4; old S-OVX: 33.4 ± 3.4, n = 4) or in the number of TH neurons which contained E2R (young S-OVX: 7.6 ± 1.0; middle-aged S-OVX: 7.2 ± 0.8; old S-OVX: 6.9 ± 1.2). These data demonstrate that ARC β-endorphin-containing perikarya are sensitive to alterations associated both with age and ovarian status; these effects are independent of one another. Our findings fail to support the hypothesis that L-OVX has a protective effect on hypothalamic neurons in older females. The subpopulation of β-endorphin neurons that contain E2R are not affected to any greater degree by age or ovarian status than the β-endorphin neuron population as a whole in the old animal.
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) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 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 ».