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3β‐HSD in songbird brain: subcellular localization and rapid regulation by estradiol
Author(s) -
Pradhan Devaleena S.,
Lau Loretta Y. M.,
Schmidt Kim L.,
Soma Kiran K.
Publication year - 2010
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2010.06954.x
Subject(s) - subcellular localization , microsome , androstenedione , mitochondrion , biology , biochemistry , compartmentalization (fire protection) , enzyme , songbird , microbiology and biotechnology , medicine , cytoplasm , endocrinology , hormone , androgen , paleontology
J. Neurochem. (2010) 115 , 667–675. Abstract The enzyme 3β‐hydroxysteroid dehydrogenase/Δ5–Δ4 isomerase (3β‐HSD) catalyzes the conversion of dehydroepiandrosterone to androstenedione, thereby playing a key role in sex steroid synthesis. In peripheral tissues, 3β‐HSD is membrane‐bound, is present in both mitochondria and microsomes, and is regulated differentially in these two subcellular compartments. In the brain, 3β‐HSD is present, but its subcellular compartmentalization is unknown. Here, in Study 1, we examined the subcellular localization of 3β‐HSD in the brain of a songbird, the zebra finch. In Study 2, in males and females, we determined whether 3β‐HSD activity in different subcellular compartments is rapidly regulated by in vitro treatment with estradiol (E 2 ), which has many rapid effects on the brain. Brain 3β‐HSD was enriched primarily in microsomes and secondarily in mitochondria and synaptosomes. In both males and females, E 2 treatment rapidly (within 5 min) inhibited 3β‐HSD activity in both mitochondria/synaptosomes and microsomes, with greater inhibition in microsomes. We also assessed the activity of 5β‐reductase, which acts on androstenedione. E 2 rapidly inhibited 5β‐reductase activity in microsomes only. This is the first study to examine the subcellular localization of 3β‐HSD in the brain, and the data demonstrate the importance of subcellular localization for the regulation of steroidogenic enzymes in the brain.