Effects evoked by prenatal exposure to Atrazine on Caiman latirostris thyroid gland are organizational and sexually dimorphic

TAVALIERI, Y.E.; LUQUE, E.H.; GALOPPO, G.H.; MUÑOZ DE TORO, M.

Mar del Plata

Congreso; XXI Reunión Anual de la Sociedad Argentina de Biología (SAB); 2019

Sociedad Argentina de Biología

Increasing thyroid disorders, mainly in women, raised the hypothesis that exposure to endocrine disruptor compounds (EDCs) and sex-related factors could influence thyroid disease epidemiology. Exposure to EDCs can cause organizational or activational effects. Caiman latirostris is a crocodilian species highly sensitive to endocrine disruption. Atrazine (ATZ) is an herbicide suspected to cause thyroid disruption. Our aims were to describe thyroid histoarchitecture, to assess sexual dimorphic features and to determine the long term effects of prenatal exposure to ATZ on thyroid gland. Male and female caimans prenatally exposed to vehicle or to 0.2ppm of ATZ were raised under controlled conditions. Biometric parameters were recorded. At prepubertal juvenile stage, caimans were sacrificed, thyroid were excised, weighed and processed until paraffin embedding. Thyrosomatic (TI) and condition indexes (CI) were calculated. The percentage of the gland occupied by stroma, epithelium or colloid; follicular hyperplasia, follicular epithelial height and expression of ERα and Androgen Receptor (AR) were assessed. No sexual dimorphism was observed in control caimans. Whereas in those ATZ exposed, sexually dimorphic responses were observed. In ATZ-females CIs were higher than in control while the opposite was observed in males. In females, ATZ exposure caused colloid depletion, increased follicular epithelial height and TI. In males, ATZ increased ERα expression. In males and females, exposure to ATZ increased the gland area occupied by stroma and the percentage of hyperplastic follicles and decreased the expression of AR. Our findings demonstrate that prenatal exposure to ATZ cause caiman thyroid disruption; the effects were organizational and observed long after exposure ended, female higher vulnerability was evidenced. These findings alert on ATZ side-effects on growth, metabolism, reproduction and development on no-target exposed organisms, particularly females.