Role of prostacyclin on steroidogenesis by frog interrenal gland |
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Authors: | Catherine Delarue Isabelle Perroteau Isabelle Lirhmann Pierre Netchitailo Franoise Homo-Delarche Hubert Vaudry |
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Institution: | Catherine Delarue, Isabelle Perroteau, Isabelle Lirhmann, Pierre Netchitailo, Françoise Homo-Delarche,Hubert Vaudry |
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Abstract: | The role of prostacyclin (PGI2) on amphibian adrenal steroidogenesis was studied
in perifused interrenal fragments from adult male frogs. Exogenous PGI2 (3×10−8 M to 3×10−5 M) and, in a lesser extent, 6-keto-PGF1α increased both corticosterone and aldosterone production in a dose-related manner. Short pulses (20 min) of 0.88 μM PGI2 administered at 90 min intervals within the same experiment did not induce any desensitization phenomenon. A prolonged administration (6 h) of PGI2 gave rise to an important increase in steroid production followed by a decline of corticosteroidogenesis. Indomethacin (IDM, 5 μM) induced a marked reduction of the spontaneous secretion of corticosteroid which confirmed the involvement of endogenous PGs in the process of corticosteroid biosynthesis. The IDM-induced blockade of corticosterone and aldosterone secretion was totally reversed by administration of exogenous PGI2 in our model. Angiotensin II (AII) induced a massive release of 6-keto-PGF1α, the stable metabolite of PGI2. The increase of 6-keto-PGF1α preceded the stimulation of corticosterone and aldosterone secretions. In contrast, the administration of ACTH did not modify the release of 6-keto-PGF1α. These results indicate that PGI2 might be an important mediator of adrenal steroidogenesis in frog. They confirm that the corticosteroidogenic actions of ACTH and AII are mediated by different mechanisms. |
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