The effect of Nestorone on gonadotropic cells in pituitary of rats
| Autor: | Lin Cao, Yan-Qun Xu, Yan-Ling Wang, Ying Leng, Jing-De Jin, Xiao-Feng Zhao, Zhi-Ping Gu |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Ovulation
medicine.medical_specialty Pituitary gland medicine.drug_class media_common.quotation_subject Biology Gonadotropic cell Gonadotropin-Releasing Hormone Rats Sprague-Dawley Internal medicine Contraceptive Agents Female medicine Animals RNA Messenger DNA Primers media_common Drug Implants Estrous cycle Dose-Response Relationship Drug Reverse Transcriptase Polymerase Chain Reaction Obstetrics and Gynecology Luteinizing Hormone beta Subunit Rats medicine.anatomical_structure Endocrinology Reproductive Medicine Estrogen Pituitary Gland Female Gonadotropin Receptors Progesterone Luteinizing hormone Norprogesterones Endocrine gland |
| Zdroj: | Contraception. 69:505-511 |
| ISSN: | 0010-7824 |
| DOI: | 10.1016/j.contraception.2004.01.007 |
| Popis: | The implant containing Nestorone is a promising long-acting contraceptive especially suitable for lactating women. In this study, two experiments were designed to observe the effect of Nestorone on the gonadotropic cells in pituitary of rats for analyzing its antiovulation mechanism. In the first experiment, the ED 50 of Nestorone on inhibiting ovulation was found to be 1.32 mg/kg. The serum luteinizing hormone (LH) levels were significantly lower 60 h after being treated with Nestorone at 8:30–9:00 a.m. on Day 2 (D2) of estrus. Image analysis showed that the average size of the LH cells in groups treated with Nestorone at 2 or 4 mg/kg was larger than that of the control. In the group treated with 4 mg/kg, most of gonadotropic cells were regular round in shape. And, abundant granules in cytoplasm were found in those cells, which indicated that the LH stored in cells was not released. In the second experiment, the rats were treated with Nestorone at 5 mg/kg at 11:30–12:00 a.m. on D2 of estrus. The normal or higher expression of LHβ mRNA in pituitary suggested that the synthesis of LH was not inhibited by the treatment with Nestorone. The expression of PR mRNA in pituitary was significantly lower than that of the control at 33 h after treatment. This might be a direct effect of Nestorone, since there were no differences in the serum E 2 and P 4 levels between the treated and the control group. It is concluded that Nestorone prevents ovulation through inhibition of LH secretion and it has no effect on synthesis of LH. Progesterone receptors in pituitary might be involved in this process, but further study is needed to gain more evidence. |
| Databáze: | OpenAIRE |
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