Conazole fungicides inhibit Leydig cell testosterone secretion and androgen receptor activation in vitro

Maarke J.E. Roelofs*, A. Roberto Temming, Aldert H. Piersma, Martin van den Berg, Majorie B.M. van Duursen

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Conazole fungicides are widely used in agriculture despite their suspected endocrine disrupting properties. In this study, the potential (anti-)androgenic effects of ten conazoles were assessed and mutually compared with existing data. Effects of cyproconazole (CYPRO), fluconazole (FLUC), flusilazole (FLUS), hexaconazole (HEXA), myconazole (MYC), penconazole (PEN), prochloraz (PRO), tebuconazole (TEBU), triadimefon (TRIA), and triticonazole (TRIT) were examined using murine Leydig (MA-10) cells and human T47D-ARE cells stably transfected with an androgen responsive element and a firefly luciferase reporter gene. Six conazoles caused a decrease in basal testosterone (T) secretion by MA-10 cells varying from 61% up to 12% compared to vehicle-treated control. T secretion was concentration-dependently inhibited after exposure of MA-10 cells to several concentrations of FLUS (IC 50 =12.4μM) or TEBU (IC 50 =2.4μM) in combination with LH. The expression of steroidogenic and cholesterol biosynthesis genes was not changed by conazole exposure. Also, there were no changes in reactive oxygen species (ROS) formation that could explain the altered T secretion after exposure to conazoles. Nine conazoles decreased T-induced AR activation (IC 50 s ranging from 10.7 to 71.5μM) and effect potencies (REPs) were calculated relative to the known AR antagonist flutamide (FLUT). FLUC had no effect on AR activation by T. FLUS was the most potent (REP=3.61) and MYC the least potent (REP=0.03) AR antagonist. All other conazoles had a comparable REP from 0.12 to 0.38. Our results show distinct in vitro anti-androgenic effects of several conazole fungicides arising from two mechanisms: inhibition of T secretion and AR antagonism, suggesting potential testicular toxic effects. These effects warrant further mechanistic investigation and clearly show the need for accurate exposure data in order to perform proper (human) risk assessment of this class of compounds.

Original languageEnglish
Pages (from-to)271-283
Number of pages13
JournalToxicology Reports
Volume1
DOIs
Publication statusPublished - 1 Jan 2014
Externally publishedYes

Keywords

  • Androgen receptor (AR)
  • Conazole fungicides
  • Cyproconazole (PubChem CID: 86132)
  • Endocrine disrupting chemicals (EDCs)
  • Fluconazole (PubChem CID: 3365)
  • Flusilazole (PubChem CID: 73675)
  • Hexaconazole (PubChem CID: 66461)
  • MA-10 Leydig cells
  • Myclobutanil (PubChem CID: 6336)
  • Penconazole (PubChem CID: 91693)
  • Prochloraz (PubChem CID: 73665)
  • Spermatogenesis
  • Tebuconazole (PubChem CID: 86102)
  • Testosterone (T)
  • Triadimefon (PubChem CID: 39385)
  • Triticonazole (PubChem CID: 6537961)

Fingerprint

Dive into the research topics of 'Conazole fungicides inhibit Leydig cell testosterone secretion and androgen receptor activation in vitro'. Together they form a unique fingerprint.

Cite this