[Effect of DEHP and its metabolite MEHP on in vitro rat follicular development]

To use rat preantral follicle culture as a novel bioassay in order to study the effects of di-2-ethylhexyl phttmlate (DEHP) and its metabolite mono-2-ethylhexyl phthalate (MEHP) on folliculogenesis in vitro.

The preantral follicles were mechanically dissected from ovaries and equally randomized to to 96-well plates. Six dose groups were setup to be acute exposed in 2.5, 5, 10, 20, 40 and 80 microg/ml MEHP concentration, 33.7, 67.5, 125, 250, 500 and 1000 nmol/L DEHP concentration on day 2,while another control group used solvent only, each group had 16 to 20 follicles. After subsequently cultured individually for 10 days, the follicles were induced to ovulate for 20h, follicle development and oocyte maturation were observed.

Day 11 follicle survival rate (54.76% +/- 3.37%) had significantly dropped after exposure to >10 microg/ml MEHP concentration, comparing to the control group (91.57% +/- 1.32%), the difference is statistical significant (P < 0.05). There is correlation between dosage and follicle survival rate, with correlation coefficient R2 = 0.92. Abnormal follicle rate (45.24% +/- 3.37%) is remarkably higher, and the difference is statistically significant (P < 0.05) comparing to the control group. At the concentrations of >20 microg/ml MEHP, follicle growth and differentiation were dependently impaired:antral follicles (46.18% +/- 1.67%) had significantly reduced (P < 0.05) comparing to the control group (85.91% +/- 5.03%). DEHP showed no adverse effects upon follicle development, there were no significant defference between DMSO and control.

At the dose of >10 microg/ml, MEHP could inhibit the in-vitro rat follicle development, DEHP seemed no adverse effects upon follicle development.