In vitro effects of estradiol-17β, monobutyl phthalate and mono-(2-ethylhexyl) phthalate on the secretion of testosterone and insulin-like peptide 3 by interstitial cells of scrotal and retained testes in dogs

The objective was to determine the effects of estradiol-17 beta, monobutyl phthalate (MBP) and mono-(2-ethylhexyl) phthalate (MEHP) on testosterone and insulin-like peptide 3 (INSL3) secretions in cultured testicular interstitial cells isolated (enzymatic dispersion) from scrotal and retained testes of small-breed dogs. Suspension cultures were treated with estradiol-17 beta (0, 10, and 100 ng/mL), MBP (0, 0.8, and 8 mmol/L) or MEHP (0, 0.2, and 0.8 mmol/L) for 18 h, in the presence or absence of 0.1 IU/mL hCG. Testosterone (both basal and hCG-induced) and INSL3 (basal) concentrations were measured in spent medium. Effects of estradiol-17 beta, MBP, and MEHP on testosterone and INSL3 secretions were not affected (P > 0.15) by cell source (scrotal versus retained testis); therefore, data were combined and analyzed, and outcomes reported as percentage relative to the control. In testicular interstitial cells, basal testosterone secretion was increased (P < 0.01) by 100 ng/mL estradiol-17 beta (130.2 +/- 10.6% of control). Among phthalates, 0.2 and 0.8 mmol/L MEHP stimulated (P < 0.01) basal testosterone secretion (135.5 +/- 8.3% and 154.6 +/- 12.9%, respectively). However, hCG-induced testosterone secretion was inhibited (P < 0.01) by 8 mmol/L MBP (67.7 +/- 6.0%), and tended to be inhibited (P = 0.056) by 0.8 mmol/L MEHP (84.5 +/- 5.6%). Basal INSL3 secretion was inhibited (P < 0.01) by 8 mmol/L MBP (73.6 +/- 6.8%) and 0.8 mmol/L MEHP (76.9 +/- 11.3%). In conclusion, we inferred that estradiol-17 beta and certain phthalate monoesters had direct effects on secretions of testosterone and INSL3 in canine testicular interstitial cells, with no significant difference between scrotal and retained testes. (C) 2011 Elsevier Inc. All rights reserved.