Changes in Mitochondrial and Microsomal 3β-Hydroxysteroid Dehydrogenase Activity in Mouse Ovary over the Course of the Estrous Cycle1
| Autor: | Sandra D. Michael, John C. Chapman, Timothy B. Waterhouse |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Estrous cycle
endocrine system medicine.medical_specialty education.field_of_study animal structures biology urogenital system Endoplasmic reticulum Population Cell Biology General Medicine Mitochondrion Luteal phase Endocrinology Reproductive Medicine Internal medicine medicine biology.protein Microsome Cytochrome c oxidase education Inner mitochondrial membrane reproductive and urinary physiology |
| Zdroj: | Biology of Reproduction. 47:992-997 |
| ISSN: | 1529-7268 0006-3363 |
| Popis: | 3 beta-Hydroxysteroid dehydrogenase (HSD) is located in the endoplasmic reticulum and mitochondria. To determine whether the separate enzymes play different roles in steroidogenesis, the specific activity (SA) of both were measured at four different stages of the mouse estrous cycle. Microsomal HSD activity changed little throughout, averaging 8.7 +/- 0.7 nmol progesterone/min/mg protein. In contrast, mitochondrial HSD activity changed dramatically at diestrus, increasing to 14.4 nmol progesterone/min/mg protein. When measured at proestrus, estrus, and metestrus, mitochondrial HSD activity was 5.5, 7.4, and 4.5 nmol progesterone/min/mg protein, respectively. To ascertain whether the increase in mitochondrial HSD activity at diestrus could be due to a preferential induction of enzyme, its SA and the SA of a mitochondrial inner membrane enzyme, cytochrome C oxidase, were compared to the SA of a mitochondrial outer membrane enzyme, rotenone-insensitive NADH cytochrome C reductase. The SA of all three enzymes changed proportionally at diestrus, suggesting that the increase in mitochondrial HSD activity was not due to its preferential induction. Rather, we believe that the HSD activity in the mitochondrial fraction, as measured at the four stages of the estrous cycle, is a reflection of the combined contributions from an ever changing population of ovarian cells. Mitochondria from luteal cells have the highest HSD activity, and are very likely responsible for the major synthesis of progesterone during the luteal phase. |
| Databáze: | OpenAIRE |
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