Androgen signaling is essential for male reproductive development and masculinization during fetal life. Developmental exposure to endocrine disrupting chemicals, not least those that disrupt androgen action, can lead to reproductive disorders such as cryptorchidism, hypospadias, and poor fertility. In rodent toxicity studies, as well as human epidemiological studies, a general biomarker for compromised fetal androgen signaling is a shorter anogenital distance (AGD) in male offspring. Some outstanding questions, however, is if AGD is strictly sensitive to anti-androgenic effects or if other signaling pathways are involved such as estrogen signaling. Similarly, penis development and hypospadias formation also involve additional signaling pathways, but which pathways that are vulnerable to developmental exposure to endocrine disruptors are not well characterized. Therefore, we need a better molecular understanding of how these tissues are regulated and vulnerable to chemical exposures. Triticonazole, an agricultural azole fungicide, inhibits androgen receptor activity in vitro and induces short AGD in male rat offspring following gestational exposure. Though triticonazole has anti-androgenic properties, we previously showed that intrauterine exposure does not affect the transcriptome of the fetal rat testes. We thus investigated the transcriptional effects in the androgen-sensitive fetal male rat perineum and phallus. Pregnant Sprague Dawley rats were exposed via oral gavage to triticonazole (450 mg/kg bw/day) or corn oil (control) from gestational day (GD) 7-21. Fetuses (n=11-12) were collected at GD17 or GD21 and perineum and phallus were isolated. Bulk RNA barcoding and sequencing (BRB-seq) was used to analyze the transcriptomes. The transcriptomes of the developing rat perineum and phallus changed significantly during late gestation, showing distinct regional differences between these adjacent tissues and revealing 2,703 differentially expressed genes (DEGs). The transcriptional changes induced by triticonazole exposure (190 DEGs) were different between perineum and phallus, but also between different stages of development. Interestingly, DEGs not only included several androgen receptor (AR) target genes, but also estrogen receptor (ER) target genes. Our results highlight the importance of considering chemical mode of action and spatiotemporal effects when using transcriptomics approaches in characterizing complex in vivo adverse outcomes in toxicity studies. These data furthermore constitute a rich resource for studying the spatiotemporal gene networks that are involved in the development of rat perineum and phallus and the regulatory networks that can be disrupted upon exposure to xenobiotics that prevent normal masculinization of the male fetus and lead to reproductive disorders.
21 May 2022 - 24 May 2022