PFOA-Induced Ovotoxicity Differs Between Lean and Obese Mice With Impacts on Ovarian Reproductive and DNA Damage Sensing and Repair Proteins

Abstract

Perfluorooctanoic acid (PFOA) is an environmentally persistent perfluoroalkyl substance that is widely used in consumer products. Exposure to PFOA is associated with reproductive and developmental effects including endocrine disruption, delayed puberty in girls, and decreased fetal growth. In the United States, obesity affects 40% of women and 20% of girls, with higher rates in minority females. Obesity causes infertility, poor oocyte quality, miscarriage, and offspring defects. This study proposed that PFOA exposure would impact estrous cyclicity, ovarian steroid hormones, and the ovarian proteome and further hypothesized that obesity would impact PFOA-induced ovotoxicity. Female wild type (KK.Cg-a/a; lean) or KK.Cg-Ay/J mice (obese) received saline (CT) or PFOA (2.5 mg/kg) per os for 15 days beginning at 7 weeks of age. There were no effects on food intake, body weight, estrous cyclicity, serum progesterone, and heart, spleen, kidney, or uterus weight (p > .05). Ovary weight was decreased (p < .05) by PFOA exposure relative to vehicle control-treated mice in lean but not obese mice. Liquid chromatography-tandem mass spectrometry was performed on isolated ovarian protein and PFOA exposure altered the ovarian abundance of proteins involved in DNA damage sensing and repair pathways and reproduction pathways (p < .05) differentially in lean and obese mice. The data suggest that PFOA exposure alters ovary weight and differentially targets ovarian proteins in lean and obese females in ways that might reduce female fecundity.

Keywords: DNA damage sensing and repair; PFOA; obesity; ovarian proteome; ovary; reproduction.

Figure 1.

Effects of PFOA exposure on body weight in lean and obese mice. Mice were weighed prior to euthanasia. Bars represent body weight (g) ± SEM. Superscript letters indicate significant differences; p < .05. LC, lean control-treated mice; LP, lean PFOA-exposed mice; OC, obese control-treated mice; OP, obese PFOA-exposed mice. n: LC = 10; LP = 9; OC = 10; OP = 10.

Figure 2.

Effect of PFOA exposure on organ weight in lean and obese mice. After euthanasia, (A) heart, (B) spleen, (C) kidney, (D) uterus, and (E) ovary were collected and weighed (g). Bars represent mean weight ± SEM. Asterisks indicate statistical difference; p < .05. LC, lean control-treated mice; LP, lean PFOA-exposed mice; OC, obese control-treated mice; OP, obese PFOA-exposed mice. n: LC = 10; LP = 9; OC = 10; OP = 10.

Figure 3.

Ovarian steroid hormone impact of PFOA exposure in lean and obese mice. Circulating E₂ and progesterone were measured by ELISA. LC, lean control-treated mice; LP, lean PFOA-exposed mice; OC, obese control-treated mice; OP, obese PFOA-exposed mice. Bars represent mean concentration ± SEM. E₂n: LC = 10; LP = 9; OC = 10; OP = 10. P₄n: LC = 10; LP = 9; OC = 9; OP = 8.

Figure 4.

Estrous cyclicity impact of PFOA exposure in lean and obese mice. The number of days at each stage of the estrous cycle were calculated over a 14-day period and presented as a percentage. Bars represent percentage of day at proestrus (black bars), estrus (dark gray bars), and metestrus + diestrus (light gray bars) ± SEM. Asterisk indicate differences between treatments; p < .05. LC, lean control-treated mice; LP, lean PFOA-exposed mice; OC, obese control-treated mice; OP, obese PFOA-exposed mice. n: LC = 10; LP = 9; OC = 10; OP = 10.

Figure 5.

Impact of PFOA on the ovarian proteome in lean and obese mice. Total ovarian protein homogenates were analyzed by LC-MS/MS and bioinformatic comparison performed between peptides identified in (A) LC versus LP, (B) OC versus OP, and (C) LC versus OC. Dots above the solid horizontal line indicate increased (upper right corner) or decreased (upper left corner) proteins; n = 5/treatment; p < .05. D, The log2(fold-change) of proteins increased (CHERP and HPX) and decreased (OGFR and AHSG) by PFOA in both lean (gray bar) and obese (black bar) mice.

Figure 6.

Proteins involved in DNA damage sensing and repair and reproduction that are in common or unique between treatments. The Venn diagram presents the number of ovarian proteins identified as being unique to treatment or altered in common by treatments involved in DNA damage sensing and repair and reproduction. The number of proteins in the green circle indicates the number of proteins identified in the comparison between LC and LP groups; the purple circle indicates the number of proteins identified in the comparison between OC and OP groups; and the blue circle indicates the number of proteins identified in the comparison between LC and OC groups. Overlapping areas of the circles illustrate the number of proteins that were altered by 2 or more groups.