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Oestrogen formation from androstenedione in human bone
H U Schweikert1, L Wolf, G Romalo
1Department of Internal Medicine, University of Bonn, Germany.
Clinical Endocrinology
|July 1, 1995
Summary
Aromatase enzyme activity was detected in human bone tissue, indicating that bone can produce oestrogens. This suggests a potential physiological role for oestrogens in bone health and steroid hormone action.
Area of Science:
- Endocrinology
- Bone Biology
- Steroid Metabolism
Background:
- Peripheral aromatization of androgens is the primary source of circulating estrogens in men and post-menopausal women.
- Human bone is a known target organ for both androgens and estrogens.
- Aromatase enzyme activity was investigated in human bone tissue.
Purpose of the Study:
- To assess aromatase activity in human spongiosa.
- To determine if human bone can synthesize estrogens.
- To explore the potential physiological role of bone-derived estrogens.
Main Methods:
- Aromatization was assessed by measuring estrogen formation from tritiated androstenedione.
- The tritiated water generation technique was employed for quantifying enzyme activity.
- Bone specimens were obtained from 4 men and 11 post-menopausal women.
Main Results:
- Aromatase activity was successfully detected in human bone specimens.
- The apparent Michaelis constant (Km) for aromatase ranged from 6 to 50 nM.
- The maximum velocity (Vmax) of aromatase activity varied between 0.14 and 1.23 nmol/g DNA/h.
Conclusions:
- Estrogen formation occurs within human bone tissue.
- Bone-derived estrogens may exert a physiological function in this tissue.
- This finding highlights a potential mechanism for steroid hormone action in bone.