The acute effects of mono(2-ethylhexyl)phthalate (MEHP) on testes of prepubertal Wistar rats

A single oral dose of 400 mg/kg body weight of mono(2-ethylhexyl)phthalate (MEHP), the testis toxic metabolite of di(2-ethylhexyl)phthalate. was given to 28-day-old male Wistar rats and the testis toxic effects were investiga ted 3, 6. and 12 h after exposure. Detachment and sloughing of germ cells w ere observed, and in the Sertoli cells the cytoplasmatic intermediate filam ent vimentin collapsed. In the immunohistochemical investigation the androg en receptor distribution was unchanged between the control group and treate d groups. The expression of the testosterone-repressed-prostatic-message ge ne in rat testis increased after 3 hi but returned to control levels after 6 and 12 h. Caspase-3 activity increased 3 and 12 h after MEHP exposure. Th is increase could not be correlated to an increase in DNA fragmentation or increase in apoptotic numbers of germ cells. In conclusion, the effect of M EHP in testis is apparently not involving the androgen receptor. Vimentin l ocalisation in the Sertoli cells, and increased levels of caspase-3 activit y appear to be sensitive and early markers of MEHP testis toxicity. (C) 200 1 Elsevier Science Ireland Ltd. All rights reserved.