Chronic dietary exposure to a glyphosate-based herbicide alters ovarian functions in young female broilers

Abstract

Glyphosate (GLY)-based herbicide (GBH) formulations are widely used pesticides in agriculture. The European Union recently decided to extend the use of GLY in Europe until 2034. Previously, we showed that chronic dietary GBH exposure in adult hens resulted in a reversible increase in early mortality in chicken embryos. In this present study, we investigated the GBH effects on metabolism and ovarian functions by using a transcriptomic approach in vivo in young female broilers and in vitro in ovarian explant cultures. We exposed 11-day-old female broilers to 13 mg GLY equivalent/kg body weight/day (GBH13, n = 20), 34 mg GLY equivalent/kg body weight/day (GBH34, n = 20), or a standard diet (control [CT], n = 20) for 25 days. These two GBH concentrations correspond to approximatively one eighth and one third of the no observed adverse effect level (NOAEL) as defined by European Food Safety Authority in birds. During this period, we evaluated body weight, fattening, food intake, and the weight of organs (including the ovaries). Chronic dietary GBH exposure dose dependently reduced food intake, body weight, and fattening, but increased oxidative stress and relative ovary weight. We analyzed the ovarian gene expression profile in CT, GBH13, and GBH34 broilers with RNA sequencing and showed that differentially expressed genes are mainly enriched in pathways related to cholesterol metabolism, steroidogenesis, and RNA processing. With quantitative polymerase chain reaction and western blotting, we confirmed that GBH decreased ovarian STAR and CYP19A1 messenger RNA and protein expression, respectively. Furthermore, we confirmed that GBH altered steroid production in ovarian explants. We have identified potential regulatory networks associated with GBH. These data provide valuable support for understanding the ovarian transcriptional regulatory mechanism of GBH in growing broilers.