Glyphosate is a broad spectrum herbicide that is effective against weeds, especially in association with transgenic glyphosate resistant crop systems, and represents approximately 30% of all herbicides used in agriculture. It was demonstrated that glyphosate has an activity of endocrine-chemical disruptor (ECD) in the reproductive axis, altering the production of testosterone and causing disturbances on the reproductive development of male offspring from dams treated during the gestational period. The hypothalamic-pituitary-thyroid axis is quite sensitive to be a target of many ECDs, but it is not known if glyphosate may affect it. To evaluate this possibility 90-day-old female Wistar rats were mated in a monogamous couples and the beginning of gestation (GD1 gestational day) was confirmed by vaginal smear containing spermatozoa. Glyphosate Roundup Transorb was diluted in a watery suspension and administered to the mothers once a day, p.o. from GD18 to PND5 (post natal day) (50 mg/kg or 0 mg/kg for control group). The male offspring were decapitated at PND60 and the pituitaries submitted to analysis of beta TSH and alpha subunit mRNA by RT/qPCR and to protein content by Western Blotting. The genes RPL19 and GAPDH were used as internal control and the results were analyzed by Students t-test (P<0.05). Perinatal exposure to glyphosate decreased the content of beta TSH mRNA and increased its protein content in the pituitary, without altering the expression of alpha subunit. These results show for the first time the effects of glyphosate in the pituitary-thyroid axis and demonstrated that the EDC effect of glyphosate is not restricted to the reproductive axis. It is not known whether the dose used in this study is in fact the levels of exposure of population to the glyphosate herbicide. However, it was shown that women occupationally exposed to this herbicide have reproductive disorders and may also need necessary to consider in the future the possibility of disturbances in the thyroid function.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details unavailable.