Ovarian and feto-placental factors and the regulation of prolactin release during pregnancy in the rat
| Autor: | N. Alonso, G. A. Jahn, R. P. Deis |
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| Rok vydání: | 1986 |
| Předmět: |
endocrine system
Embryology medicine.medical_specialty Ovariectomy Endogeny Normal values Prolactin cell Endocrinology Corpus Luteum Pregnancy Internal medicine Animals Medicine Secretion Progesterone reproductive and urinary physiology Estradiol urogenital system business.industry Ovary Obstetrics and Gynecology Rats Inbred Strains Cell Biology medicine.disease Prolactin Rats Blockade Reproductive Medicine Ovariectomized rat Female business hormones hormone substitutes and hormone antagonists |
| Zdroj: | Reproduction. 77:125-133 |
| ISSN: | 1741-7899 1470-1626 |
| DOI: | 10.1530/jrf.0.0770125 |
| Popis: | Administration of progesterone (5 or 10 mg) to pregnant rats increased serum prolactin significantly on the afternoon of Days 4, 6, 7 and 8 of pregnancy, but had no effect on later days. On Day 10 progesterone administration increased serum prolactin only in rats treated with oestrogen the day before. A similar treatment with oestrogen and progesterone was unable to stimulate secretion on the afternoon of Day 13 of pregnancy. In rats from which the corpora lutea had been unilaterally removed and hence endogenous progesterone levels were 50% of the normal values, or in those that carried 4 conceptuses, progesterone treatment after oestradiol priming was partly effective in inducing prolactin release on Day 13. However, in rats ovariectomized, with bilateral excision of the corpora lutea, or with 2 conceptuses left, treatment with ovarian steroids markedly increased serum prolactin values. By Day 13 all the rats from the ovariectomized group or with bilateral excision of the corpora lutea had aborted. On Day 13, therefore, the high serum concentrations of feto-placental factors and of progesterone are responsible for the blockade of the spontaneous and ovarian steroid-induced prolactin release. On the other hand, on Day 16 of pregnancy the decrease of circulating progesterone by excision of the corpora lutea or by ovariectomy followed by oestradiol treatment significantly increased serum prolactin on Day 17. Removal of all the conceptuses did not modify the effects of these treatments. The present results demonstrate different roles of progesterone upon the control of prolactin secretion. After a stimulatory action during the first days of pregnancy, there is a change to an inhibitory control at the end of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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