Effects of Exposure to Acetaminophen and Ibuprofen on Fetal Germ Cell Development in Both Sexes in Rodent and Human Using Multiple Experimental Systems.

Background: Analgesic exposure during pregnancy may affect aspects of fetal gonadal development that are targeted by endocrine disruptors.

Objectives: We investigated whether therapeutically relevant doses of acetaminophen and ibuprofen affect germ cell (GC) development in human fetal testes/ovaries using and xenograft approaches.

Methods: First-trimester human fetal testes/ovaries were cultured and exposed to acetaminophen or ibuprofen (7 d). Second-trimester human fetal testes were xenografted into mice and exposed to acetaminophen (1 or 7 d), or ibuprofen (7 d). To determine mechanism of action, a human GC tumor–derived cell line (NTera2) exhibiting fetal GC characteristics was used in addition to and rat models.

Results And Discussion: Gonocyte (TFAP2C) number was reduced relative to controls in first-trimester human fetal testes exposed in vitro to acetaminophen (-28%) or ibuprofen (-22%) and also in ovaries exposed to acetaminophen (-43%) or ibuprofen (-49%). Acetaminophen exposure reduced gonocyte number by 17% and 30% in xenografted second-trimester human fetal testes after treatment of host mice for 1 or 7 d, respectively. NTera2 cell number was reduced following exposure to either analgesic or prostaglandin E (PGE) receptor antagonists, whereas PGE agonists prevented acetaminophen-induced reduction in NTera2 cell number. Expression of GC pluripotency genes, and genes that regulate DNA/histone methylation, also differed from controls following analgesic and PGE receptor antagonist exposures. Gene expression changes were observed in rat fetal testis/ovary cultures and after in vivo acetaminophen exposure of pregnant rats. For example, expression of the epigenetic regulator , was increased following exposure to acetaminophen in human NTera2 cells, rat fetal testis/ovary cultures, and in fetal testes and ovaries after in vivo exposure of pregnant rats, indicating translatability across experimental models and species.

Conclusions: Our results demonstrate evidence of PGE-mediated effects of acetaminophen and ibuprofen on GC/NTera2 cells, which raises concerns about analgesic use during human pregnancy that warrant further investigation. https://doi.org/10.1289/EHP2307.