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Estrogen suppression in males: metabolic effects
N Mauras1, K O O'Brien, K O Klein
1Nemours Research Programs at the Nemours Children's Clinic, Jacksonville, Florida 32207, USA. nmauras@nemours.org
The Journal of Clinical Endocrinology and Metabolism
|July 21, 2000
Summary
Estrogen suppression in males using an aromatase inhibitor did not affect body composition or protein synthesis. However, it did impact the pituitary-gonadal axis and hormone levels, suggesting a regulatory role for estrogen.
Area of Science:
- Endocrinology
- Male Reproductive Health
- Metabolic Research
Background:
- Testosterone (T) deficiency causes catabolic effects in men, but the role of estrogens in male anabolism is unclear.
- Estrogens are known to influence various physiological processes, including bone metabolism and hormonal feedback loops.
Purpose of the Study:
- To investigate the metabolic effects of selective estrogen suppression in males using the aromatase inhibitor Arimidex (Anastrozole).
- To determine if estrogens play a significant role in whole-body anabolism and body composition in males.
Main Methods:
- A dose-response study with Arimidex in 12 males, followed by a 10-week study in eight males (aged 15-22).
- Methods included isotopic infusions for protein and calcium kinetics, indirect calorimetry, dual-energy x-ray absorptiometry, and growth factor measurements.
- Hormonal levels (estradiol, testosterone, LH, FSH) and bone markers were assessed.
Main Results:
- Selective estrogen suppression (48% decrease in estradiol) did not significantly alter body composition, protein synthesis/degradation, substrate oxidation, muscle strength, or calcium kinetics.
- Insulin-like growth factor I decreased by 18%, while testosterone increased by 58%.
- Estrogen suppression regulated the pituitary-gonadal axis, increasing LH and FSH concentrations.
Conclusions:
- Estrogens do not significantly contribute to body composition and protein synthesis changes related to androgen levels in males.
- Estrogen is a key regulator of the pituitary-gonadal feedback axis in males.
- Short-term aromatase inhibition at this level did not negatively impact bone calcium turnover.