Atrazine disrupts gonadal development in a live-bearing lizard

Abstract

Atrazine (ATZ) is an endocrine disruptor that increases aromatase activity. In viviparous (live-bearing) vertebrates, embryos may be exposed to endocrine disruptors via the placenta. Studies of the effects of ATZ in viviparous amniotes have focused on rodents, which are relatively insensitive to ATZ: studies on other viviparous amniotes are therefore required. We aimed to determine the effects of gestational exposure to a single dose of ATZ at 10 ppb on gonadal development in a viviparous skink, Niveoscincus metallicus. Pregnant skinks were exposed to ATZ, the synthetic estrogen diethylstilbestrol (DES) (positive control), vehicle solvent or no treatment. Gonads were examined histologically at birth. Females born to ATZ and DES exposed mothers were more likely to exhibit ovaries with abnormal oocytes than were females whose mothers received vehicle solvent or no treatment. Males born to ATZ and DES exposed mothers were equally more likely to exhibit testes devoid of germ cells with reduced organization of seminiferous tubules (ST) compared to males born to mothers receiving vehicle solvent or no treatment. However, ATZ treatment significantly increased the number of male neonates born with testicular lesions compared to males born to mothers in any other group. We conclude that atrazine disrupts gonadal differentiation in the viviparous lizard, N. metallicus. The similar effects of DES and ATZ suggest that the developmental effects of ATZ in N. metallicus reflect increased estrogen signaling. Atrazine should be used with caution as exposure of wildlife to this EDC is likely to have adverse effects on reproductive health.

Characterization of evolutionary trend in squamate estrogen receptor sensitivity

“…Furthermore, endocrine disruptions by xenoestrogen presence have also been extensively reported in reptiles; most famously, American alligator population that experienced an exposure to estrogenic pesticide displayed various lowered reproductive capability, including reduced fertility, hormonal imbalance, and abnormal development of accessory organs (Guillette et al, 1994 andGuillette et al, 1996). Endocrine disrupting chemical action has been documented in several other reptile groups as well (Bergeron et al, 1994 andParsley et al, 2015).…”

Sex Determination and Ovarian Development in Reptiles and Amphibians: From Genetic Pathways to Environmental Influences

“…Mechanistic reasons for the opposite effects of low versus high doses are unknown. Other alterations to ovarian morphology have been observed in embryonic lizards exposed to maternal atrazine [Parsley et al, 2015a], diethylbestrol [Parsley et al, 2015b], or injected with cadmium [Simoniello et al, 2010]. These exposures often induced altered cellular structure of the ovary and disrupted oogenesis and folliculogenesis.…”

Histological Analysis of Gonadal Ridge Development and Sex Differentiation of Gonads in Three Gecko Species

“…It comprises 11,549 species (http://www.reptile-database.org/db-info/SpeciesStat.html (accessed on December 2022)), which accounts for 96.7% of the currently known reptile species. Among squamates, experimental studies indicated the disruptive effect of atrazine on gonadal development in the skink Niveoscincus metallicus [13]. Some structural data on gonadal development are known for the skink Niveoscincus ocellatus, the anguid lizard Barisia imbricata, the agamas Pogona vitticeps and Calotes versicolor, and the phrynosomatid lizard Sceloporus aeneus [14][15][16][17].…”