Hypercholesterolemia with consumption of PFOA-laced Western diets is dependent on strain and sex of mice

Abstract

Perfluorooctanoic acid (PFOA) is a man-made surfactant with a number of industrial applications. It has a long half-life environmentally and biologically. Past studies suggest a direct relationship between plasma cholesterol and PFOA serum concentrations in humans and an inverse one in rodents fed standard rodent chow, making it difficult to examine mechanisms responsible for the potential PFOA-induced hypercholesterolemia and altered sterol metabolism. To examine dietary modification of PFOA-induced effects, C57BL/6 and BALB/c mice were fed PFOA in a fat- and cholesterol-containing diet. When fed these high fat diets, PFOA ingestion resulted in marked hypercholesterolemia in male and female C57BL/6 mice and less robust hypercholesterolemia in male BALB/c mice. The PFOA-induced hypercholesterolemia appeared to be the result of increased liver masses and altered expression of genes associated with hepatic sterol output, specifically bile acid production. mRNA levels of genes associated with sterol input were reduced only in C57BL/6 females, the mice with the greatest increase in plasma cholesterol levels. Strain-specific PFOA-induced changes in cholesterol concentrations in mammary tissues and ovaries paralleled changes in plasma cholesterol levels. mRNA levels of sterol-related genes were reduced in ovaries of C57BL/6 but not in BALB/c mice and not in mammary tissues. Our data suggest that PFOA ingestion leads to hypercholesterolemia in mice fed fat and cholesterol and effects are dependent upon the genetic background and gender of the mice with C57BL/6 female mice being most responsive to PFOA.

Keywords: C8; PFAS; PFC; cholesterol; dietary fat; perfluorooctanoic acid.

Fig. 1

Plasma cholesterol concentrations in C57BL/6 (A) and BALB/c (B) male and female mice. Mice were weaned and fed diets containing fat plus cholesterol. Half of the mice received no dietary PFOA and half received 3.5 mg/kg diet so that mice would consume ≈1 mg/kg body weight. After 6 weeks of dietary treatment, mice were anesthetized, exsanguinated and plasma collected. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05).

Fig. 2

Lipoprotein-cholesterol in C57BL/6 and BALB/c male and female mice. Plasma collected in animals described in Fig. 1 was pooled by group and lipoproteins separated by FPLC. Cholesterol content in each fraction was measured enzymatically.

Fig. 3

Cholesterol concentration in the livers of C57BL/6 (A) and BALB/c (B) male and female mice. Livers were collected from mice described in Fig. 1 and cholesterol measured by gas chromatography. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05).

Fig. 4

Cholesterol concentration in the mammary tissues and ovaries of C57BL/6 (A) and BALB/c (B) female mice. Tissues were collected from mice described in Fig. 1 and cholesterol measured by gas chromatography. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05) and by # (P = 0.069).

Fig. 5

Relative mRNA levels of genes involved in sterol metabolism of livers of C57BL/6 (A, C) and BALB/c (B, D) male and female mice. Livers were collected from mice described in Fig. 1 and mRNA levels measured by real time PCR using cyclophilin as our housekeeping gene. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05).

Fig. 6

Relative mRNA levels of genes involved in sterol metabolism of mammary tissues and ovaries of C57BL/6 (A, C) and BALB/c (B, D) female mice. Tissues were collected from mice described in Fig. 1 and mRNA levels measured by real time PCR using cyclophilin as our housekeeping gene. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05) and by # (P = 0.056).

Fig. 7

Relative mRNA levels of genes involved PPARα signaling in livers of C57BL/6 (A, C) and BALB/c (B, D) male and female mice. Livers were collected from mice described in Fig. 1 and mRNA levels measured by real time PCR using cyclophilin as our housekeeping gene. Data represent averages ± SEM (n = 5–6). Differences from mice fed control diets are depicted by * (P < 0.05) and # (P = 0.08).