Changes in mitochondrial and microsomal 3 beta-hydroxysteroid dehydrogenase activity in mouse ovary over the course of the estrous cycle.
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.
Chapman
J C
JC
Department of Biological Sciences, State University of New York, Binghamton 13902-6000.
Waterhouse
T B
TB
Michael
S D
SD
D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism; D004958:Estradiol / Q000097:blood; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000096:biosynthesis; D007521:Isocitrate Dehydrogenase / Q000096:biosynthesis; D051379:Mice; D008809:Mice, Inbred C3H; D008861:Microsomes / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000096:biosynthesis; D010053:Ovary / Q000378:metabolism*; D010734:Phosphogluconate Dehydrogenase / Q000096:biosynthesis; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D013739:Testosterone / Q000097:blood
D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D015096:3-Hydroxysteroid Dehydrogenases; D007521:Isocitrate Dehydrogenase; D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV