Mono-(2-ethylhexyl) phthalate (MEHP) induces spermatogenic cell apoptosis in guinea pig testes at prepubertal stage in vitro

Abstract

The effects of mono-(2-ethylhexyl) phthalate (MEHP), an active metabolite of di-(2-ethylhexyl) phthalate (DEHP), on prepubertal guinea pig testes in vitro were investigated. The testes of 35-day-old guinea pigs were surgically excised. They were seeded in a defined medium containing antibiotics and administered MEHP at concentrations of 1, 10, and 100 nmol/ml, respectively. The control groups were administered a similar volume of corn oil vehicle. The tissues were incubated for 3, 6, and 9 h. The specimens were collected at 3, 6, and 9 h after treatment. They were fixed in 4% paraformaldehyde or 5% glutaraldehyde. For quantitation of the apoptotic spermatogenic cells, the terminal dUTP nick end-labeling (TUNEL) staining was performed by light microscopy. Detachment and displacement of spermatogenic cells, thin seminiferous epithelia, and Sertoli cell vacuolization were observed. Maximal testicular damage was recognized at 100 nmol/ml and 9 h after MEHP treatment. The percentage (%) of apoptotic spermatogenic cells significantly increased at 3, 6, and 9 h after treatment, compared to the control groups. Because the loss of spermatogenic cells by MEHP treatment varies among species, the present study, using guinea pigs, was designed and conducted to obtain further information.