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Androgen and 19-norandrogen aromatization by equine and human placental microsomes.
Abstract: The ability of equine and human placental microsomes to aromatize testosterone and 19-nortestosterone was studied. When 3 microM [1 beta,2 beta-3H]testosterone was used as substrate, the specific activity of equine placental microsomal aromatase was 2.5 times higher than that of the human microsomal enzyme. Although 19-nortestosterone was aromatized 67 times more rapidly by equine than by human aromatase, we found that equine aromatase exhibited a markedly weaker affinity for this substrate than did the human enzyme. Competitive inhibition of testosterone aromatization by 19-nortestosterone occurred with both equine and human aromatases. While having no effect on mare placental microsomes, Na+ and K+ (500 mM) stimulated testosterone aromatization by human placental microsomes by 73 and 52% respectively. If indeed a single enzyme is responsible for the aromatization of testosterone and 19-nortestosterone, which seems to be the case in both equine and human placental aromatase, our results show that differences in the structure of the active sites exist between equine and human aromatases.
Publication Date: 1989-11-01 PubMed ID: 2601340DOI: 10.1016/0022-4731(89)90245-8Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Comparative Study
- Journal Article
Summary
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The research paper explores the rate and efficiency of testosterone and 19-nortestosterone aromatization by equine and human placental microsomes, revealing interesting differences between the two.
Testosterone Aromatization Analysis
- The research was initiated to study how equine and human placental microsomes aromatize testosterone and 19-nortestosterone.
- The enzyme aromatase was used to convert testosterone into estradiol. The study found that the specific activity of equine placental microsomal aromatase was 2.5 times higher than that of the human equivalent when given the same amount (3 microM) of testosterone.
19-nortestosterone Aromatization Analysis
- Results showed that when 19-nortestosterone was the substrate, it was aromatized 67 times more rapidly by equine aromatase compared to human aromatase.
- Yet, interestingly, it was observed that equine aromatase displayed a much weaker affinity for 19-nortestosterone than the human enzyme.
- Additionally, it was also observed that 19-nortestosterone competitively inhibited testosterone aromatization with both equine and human aromatases.
Effects of Sodium and Potassium
- The study further looked into the effects of sodium (Na+) and potassium (K+) on testosterone aromatization. These two elements had no effect on mare placental microsomes.
- However, they did stimulate testosterone aromatization in human placental microsomes, with sodium and potassium increasing aromatization by 73% and 52% respectively.
Comparison of Equine and Human Aromatases
- Contrary to the possibility of a single enzyme being responsible for the aromatization of both testosterone and 19-nortestosterone, results seem to suggest that there could be structural differences in the active sites between the equine and human aromatases.
In summary, this research provides novel insights into the aromatization activity of equine and human placental microsomes, pointing towards notable differences and similarities in their function and structure.
Cite This Article
APA
Dintinger T, Gaillard JL, Moslemi S, Zwain I, Silberzahn P.
(1989).
Androgen and 19-norandrogen aromatization by equine and human placental microsomes.
J Steroid Biochem, 33(5), 949-954.
https://doi.org/10.1016/0022-4731(89)90245-8 Publication
Researcher Affiliations
- Laboratoire de Biochimie, URA CNRS 59, Université, Caen, France.
MeSH Terms
- Animals
- Aromatase / metabolism
- Aromatase Inhibitors
- Female
- Horses
- Humans
- Kinetics
- Microsomes / metabolism
- Nandrolone / blood
- Nandrolone / metabolism
- Placenta / metabolism
- Pregnancy
- Testosterone / blood
- Testosterone / metabolism
Citations
This article has been cited 4 times.- Defarge N, Spiroux de Vendômois J, Séralini GE. Toxicity of formulants and heavy metals in glyphosate-based herbicides and other pesticides. Toxicol Rep 2018;5:156-163.
- Defarge N, Takács E, Lozano VL, Mesnage R, Spiroux de Vendômois J, Séralini GE, Székács A. Co-Formulants in Glyphosate-Based Herbicides Disrupt Aromatase Activity in Human Cells below Toxic Levels. Int J Environ Res Public Health 2016 Feb 26;13(3).
- Attardi BJ, Pham TC, Radler LC, Burgenson J, Hild SA, Reel JR. Dimethandrolone (7alpha,11beta-dimethyl-19-nortestosterone) and 11beta-methyl-19-nortestosterone are not converted to aromatic A-ring products in the presence of recombinant human aromatase. J Steroid Biochem Mol Biol 2008 Jun;110(3-5):214-22.
- Richard S, Moslemi S, Sipahutar H, Benachour N, Seralini GE. Differential effects of glyphosate and roundup on human placental cells and aromatase. Environ Health Perspect 2005 Jun;113(6):716-20.
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