The Paradoxical Stimulatory Effect of Morphine on LH Secretion Is Dose-Dependent and Naloxone-Reversible
Notice bibliographique
Résumé
We previously observed that morphine stimulated luteinizing hormone (LH) secretion from ovariectomized rats when administered intravenously at a dose of 10 mg/kg body weight. The objectives of the present study were to determine: (1) if this paradoxical effect of morphine on LH secretion could be antagonized by naloxone; (2) whether β-endorphin also stimulated LH secretion under similar conditions; (3) what influence, if any, the ovaries have on the expression of this opiate-induced LH secretion, and (4) whether this paradoxical effect of morphine extended to prolactin (PRL) secretion. An intravenous injection of morphine, 10 mg/kg body weight, to ovariectomized rats acutely increased both plasma LH and PRL concentrations. The LH and PRL responses were completely antagonized by the concurrent administration of the opiate antagonist naloxone (1 mg/kg body weight). In contrast, morphine suppressed LH concentrations and had no effect on PRL levels when injected at a dose of 1.0 mg/kg body weight. Intravenous injections of β-endorphin, 1 mg/kg body weight, increased PRL concentrations to a level comparable to that observed following morphine, 10 mg/kg body weight, and produced a transient but insignificant inhibition of LH release. Intraventricular injections of much lower doses of β-endorphin resulted in a dose-dependent suppression of LH release and a dose-dependent stimulation of PRL release in ovariectomized rats. Intravenous administrations of morphine (10 mg/ kg), but not β-endorphin (1 mg/kg), to normal female rats resulted in a 2-fold increase in LH concentrations similar to that observed in ovariectomized rats, whereas both treatments similarly increased PRL concentrations. We conclude from these results that (1) morphine stimulation of LH secretion is dose-dependent and naloxone-reversible; (2) gonadal status does not appear to be an important factor, since this paradoxical effect of morphine was observed both in castrated and gonad-intact female rats: (3) β-endorphin and morphine affect LH and PRL secretion by different mechanisms, since none of the β-endorphin doses tried was able to stimulate LH secretion, even though these doses produced PRL responses that encompassed the PRL response to morphine. Furthermore, the relative potencies of β-endorphin and morphine with regard to PRL and LH secretion are different. β-Endorphin stimulated PRL secretion at a dose lower than that required to inhibit LH secretion, whereas morphine inhibited LH secretion at a dose lower than that required to stimulate PRL secretion. (4) The typical PRL response to morphine administration is maintained, even though the LH response was reversed. Based on these results, we believe that the hypothesis of both stimulatory and inhibitory opioid influences on LH secretion is tenable but would suggest an endogenous opiate other than β-endorphin as candidate.
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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 tête enseignante, 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 ».