Carryover Effects of Acute DEHP Exposure on Ovarian Function and Oocyte Developmental Competence in Lactating Cows

PLoS One. 2015 Jul 8;10(7):e0130896. doi: 10.1371/journal.pone.0130896. eCollection 2015.

Abstract

We examined acute exposure of Holstein cows to di(2-ethylhexyl) phthalate (DEHP) and its carryover effects on ovarian function and oocyte developmental competence. Synchronized cows were tube-fed with water or 100 mg/kg DEHP per day for 3 days. Blood, urine and milk samples were collected before, during and after DEHP exposure to examine its clearance pattern. Ovarian follicular dynamics was monitored through an entire estrous cycle by ultrasonographic scanning. Follicular fluids were aspirated from the preovulatory follicles on days 0 and 29 of the experiment and analyzed for phthalate metabolites and estradiol concentration. The aspirated follicular fluid was used as maturation medium for in-vitro embryo production. Findings revealed that DEHP impairs the pattern of follicular development, with a prominent effect on dominant follicles. The diameter and growth rate of the first- and second-wave dominant follicles were lower (P < 0.05) in the DEHP-treated group. Estradiol concentration in the follicular fluid was lower in the DEHP-treated group than in controls, and associated with a higher number of follicular pathologies (follicle diameter >25 mm). The pattern of growth and regression of the corpus luteum differed between groups, with a lower volume in the DEHP-treated group (P < 0.05). The follicular fluid aspirated from the DEHP-treated group, but not the controls, contained 23 nM mono(2-ethylhexyl) phthalate. Culturing of cumulus oocyte complexes in the follicular fluid aspirated from DEHP-treated cows reduced the proportion of oocytes progressing to the MII stage, and the proportions of 2- to 4-cell-stage embryos (P < 0.04) and 7-day blastocysts (P < 0.06). The results describe the risk associated with acute exposure to DEHP and its deleterious carryover effects on ovarian function, nuclear maturation and oocyte developmental competence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Cell Nucleus / metabolism
  • Corpus Luteum / drug effects
  • Corpus Luteum / metabolism
  • Cumulus Cells / cytology
  • Cumulus Cells / drug effects
  • Cytoplasm / metabolism
  • Diethylhexyl Phthalate / blood
  • Diethylhexyl Phthalate / chemistry*
  • Diethylhexyl Phthalate / urine
  • Estradiol / metabolism
  • Estrous Cycle
  • Female
  • Follicular Fluid
  • Lactation
  • Meiosis
  • Milk / chemistry
  • Oocytes / cytology*
  • Oocytes / drug effects
  • Ovarian Follicle / diagnostic imaging
  • Ovarian Follicle / drug effects*
  • Ovary / drug effects*
  • Phthalic Acids / chemistry
  • Regression Analysis
  • Tandem Mass Spectrometry
  • Ultrasonography

Substances

  • Phthalic Acids
  • Estradiol
  • phthalic acid
  • Diethylhexyl Phthalate

Grants and funding

The study was conducted in the framework of The Hebrew University Center of Excellence in Agriculture and Environmental Health funded by the Environment and Health Fund, Jerusalem, Israel, and by the Israeli Dairy Board (project #821-130-10). The author who received the funding is ZR. AXYS Analytical Services Inc., provided support in the form of salaries for authors DP and CT, but did not have any additional role in the study design, data collection and data analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.