Testosterone synthesis and adenylate cyclase activity in the early human fetal testis appear to be independent of human chorionic gonadotropin control

R. A. Word, F. W. George, J. D. Wilson, B. R. Carr

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Abstract

Androgen secretion by the fetal testis is essential for male phenotypic differentiation. In the human fetus testosterone formation is initiated soon after the differentiation of the testis (~8 weeks of gestation), and the maximal testosterone content in fetal testes is achieved between 10 and 15 weeks of fetal life. The testosterone content of the fetal testis declines at the beginning of the third trimester and remains low until after birth. In an effort to understand the regulation of the onset of testosterone formation in the human fetal testis we meausred adenylate cyclase activity in response to hCG stimulation in homogenates of fetal testes obtained from first and second trimester human abortuses. Basal adenylate cyclase activity was 50 pmol/mg protein·min at 10 weeks gestation, the peak activity was 137 pmol/mg protein·min at 12 weeks gestation, and activity declined thereafter to 8 pmol/mg protein·min by 16 weeks gestation. NaF-stimulated (0.6 mmol/L) and forskolin-stimulated (50 μmol/L) activities were 4- to 8-fold greater than basal adenylate cyclase activities. The maximal forskolin-stimulated activity occurred at 11 weeks (803 pmol/mg protein·min), and it fell to 35 pmol/mg protein·min by 17 weeks gestation. In contrast, hCG-stimulated (1 μmol/L) adenylate cyclase activity was only slightly greater than basal rates at all ages examined. In addition, hCG did not stimulate baseline testosterone formation in minces of testes obtained between 12 and 18 weeks of gestation. These findings suggest that the onset of testosterone formation in human fetal testes may be independent of gonadotropin control.

Original languageEnglish (US)
Pages (from-to)204-208
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Volume69
Issue number1
StatePublished - 1989

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Chorionic Gonadotropin
Adenylyl Cyclases
Testosterone
Testis
Pregnancy
Colforsin
Gonadotropins
Androgens
Third Pregnancy Trimester
Second Pregnancy Trimester
First Pregnancy Trimester
Fetus
Parturition

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology, Diabetes and Metabolism

Cite this

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abstract = "Androgen secretion by the fetal testis is essential for male phenotypic differentiation. In the human fetus testosterone formation is initiated soon after the differentiation of the testis (~8 weeks of gestation), and the maximal testosterone content in fetal testes is achieved between 10 and 15 weeks of fetal life. The testosterone content of the fetal testis declines at the beginning of the third trimester and remains low until after birth. In an effort to understand the regulation of the onset of testosterone formation in the human fetal testis we meausred adenylate cyclase activity in response to hCG stimulation in homogenates of fetal testes obtained from first and second trimester human abortuses. Basal adenylate cyclase activity was 50 pmol/mg protein·min at 10 weeks gestation, the peak activity was 137 pmol/mg protein·min at 12 weeks gestation, and activity declined thereafter to 8 pmol/mg protein·min by 16 weeks gestation. NaF-stimulated (0.6 mmol/L) and forskolin-stimulated (50 μmol/L) activities were 4- to 8-fold greater than basal adenylate cyclase activities. The maximal forskolin-stimulated activity occurred at 11 weeks (803 pmol/mg protein·min), and it fell to 35 pmol/mg protein·min by 17 weeks gestation. In contrast, hCG-stimulated (1 μmol/L) adenylate cyclase activity was only slightly greater than basal rates at all ages examined. In addition, hCG did not stimulate baseline testosterone formation in minces of testes obtained between 12 and 18 weeks of gestation. These findings suggest that the onset of testosterone formation in human fetal testes may be independent of gonadotropin control.",
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AU - George, F. W.

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AU - Carr, B. R.

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