Hypothalamic transcriptomic alterations in male and female California mice (Peromyscus californicus) developmentally exposed to bisphenol A or ethinyl estradiol

Abstract

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) prevalent in many household items. Rodent models and human epidemiological studies have linked this chemical to neurobehavior impairments. In California mice, developmental exposure to BPA results in sociosexual disorders at adulthood, including communication and biparental care deficits, behaviors that are primarily regulated by the hypothalamus. Thus, we sought to examine the transcriptomic profile in this brain region of juvenile male and female California mice offspring exposed from periconception through lactation to BPA or ethinyl estradiol (EE, estrogen present in birth control pills and considered a positive estrogen control for BPA studies). Two weeks prior to breeding, P₀ females were fed a control diet, or this diet supplemented with 50 mg BPA/kg feed weight or 0.1 ppb EE, and continued on the diets through lactation. At weaning, brains from male and female offspring were collected, hypothalamic RNA isolated, and RNA-seq analysis performed. Results indicate that BPA and EE groups clustered separately from controls with BPA and EE exposure leading to unique set of signature gene profiles. Kcnd3 was downregulated in the hypothalamus of BPA- and EE-exposed females, whereas Tbl2, Topors, Kif3a, and Phactr2 were upregulated in these groups. Comparison of transcripts differentially expressed in BPA and EE groups revealed significant enrichment of gene ontology terms associated with microtubule-based processes. Current results show that perinatal exposure to BPA or EE can result in several transcriptomic alterations, including those associated with microtubule functions, in the hypothalamus of California mice. It remains to be determined whether these genes mediate BPA-induced behavioral disruptions.

Keywords: Brain; DOHaD; RNA‐seq; endocrine‐disrupting chemicals; estrogens.

Figure 1

PCA plot and hierarchical heatmap. (A) PCA plot of the FPKM values of differentially expressed genes shows a nonrandom distribution of points (PERMANOVA = 2e⁻⁰⁴ from 10,000 permutations), but control and EE females clustered together. (B) Hierarchical clustering and heatmap of expression ratios for the differentially expressed genes reveals primarily four groups: BPA‐treated, EE‐treated, control male, and control female groups.

Figure 2

Volcano plots. (A) Control females versus BPA‐exposed females. (B) Control females versus EE‐exposed females. (C) Control males versus BPA‐exposed males. (D) Control males versus EE‐exposed males. Significantly downregulated genes in the treatment group versus controls are depicted in blue, black genes indicate that they are not significantly different, and genes delineated in red are increased in expression relative to controls.

Figure 3

Venn diagrams. (A) Transcripts upregulated in BPA‐exposed females versus control females compared to those upregulated in EE‐exposed females versus control females. (B) Transcripts downregulated in BPA‐exposed females versus control females compared to those downregulated in EE‐exposed females versus control females. (C) Transcripts upregulated in BPA‐exposed males versus control males compared to those upregulated in EE‐exposed males versus control males. (D) Transcripts downregulated in BPA‐exposed males versus control males compared to those upregulated in EE‐exposed males versus control males.