Abstract Metronidazole is an antiprotozoal and antibacterial used in gynecology and obstetrics for the treatment of parasitic infections. However, despite having clinical use for more than three decades, questions about the safety of its use during pregnancy is not well understood. Thus, the present study evaluated the effect of metronidazole on placental and fetal development in pregnant rats. Metronidazole was orally administered by gavage at a dosage of 130 mg/kg for 7 and 14 days. Morphological analysis, morphometry and immunohistochemistry were performed at the implantation sites and placentas with 14 days of development. The results showed that in the treated group there was a significant reduction in the number of implantation sites, total placental disc area and constituent elements of the labyrinth and spongiotrophoblast layers. Histochemical analysis revealed no significant changes in the content of collagen, elastic and reticular fibers. The TUNEL test showed apoptotic activity in the implantation sites and placentas with 14 days of development independent of the treatment. There was no evidence of malformation in the neonates. However, there was a significant reduction in the number and weight of neonates in the group treated with metronidazole when compared to the control group. Thus, it is concluded that the administration of 130 mg/kg of metronidazole during pregnancy in rats, in addition to interfering with the number of implanted embryos, promotes changes in placental structure and interferes with fetal development. This suggests that this drug should be used with caution during pregnancy.

The present study had the objective of obtaining information about fertility in rats treated with dexamethasone for 10 and 15 days consecutively, to polycystic ovaries, induced by constant illumination. It was used 40 albino rats (Rattus norvegicus albinus), aged 90 days, form the lineage Wistar, which were split, randomly, in four groups, each constituted of 10 animals, namely: Group I - rats kept in a clear/dark cycle for 12/12 hours, and after 100 days submitted to fertility evaluation (control); Group II - rats kept under constant illumination during 100 days and then submitted to fertility evaluation; Group III - rats kept under constant illumination during 100 days, then treated with dexamethasone for 10 days and submitted to fertility evaluation; Group IV - rats kept under constant illumination during 100 days, then treated with dexamethasone for 15 days and submitted to fertility evaluation. The results showed that the number of implanted sites was 38(G1), 37(G2), 32(G3) and 06(G4). The reduction in group IV was due to the high mortality during the experiment, probably because of the prolonged treatment with dexamethasone. These sites presented similar histological aspects. The macroscopic analysis of the neonates haven't shown any indication of malformation. Also, abortion haven't been observed. The treatment with dexamethasone for 10 days in rats does not affect the fertility and the development of the lungs, liver and kidneys of neonates, while the administration during 15 days leads to a high maternal mortality.

El estudio tuvo el objetivo de obtener informaciones sobre la fertilidad en ratas tratadas con dexametasona por 10 y 15 días seguidos, para ovarios poliquísticos, inducidos por iluminación constante. Se utilizó 40 ratas albinas (Rattus norvegicus albinus) con 90 días de edad, del linaje Wistar, las cuales fueron divididas, en cuatro grupos, cada uno constituido por 10 animales: Grupo I - ratas mantenidas en ciclo claro/oscuro de 12/12 horas, y después de 100 días sometidas a la evaluación de la fertilidad (control); Grupo II- ratas mantenidas bajo iluminación constante, durante 100 días, y luego sometidas a la evaluación de la fertilidad ; Grupo III - ratas mantenidas bajo iluminación constante, a lo largo de 100 días, y posteriormente tratadas con dexametasona por diez días, y sometidas a la evolución de la fertilidad; Grupo IV - ratas mantenidas bajo iluminación constante, durante 100 días, en seguida tratadas con dexametasona por 15 días, y sometidas a la evaluación de la fertilidad. Los resultados mostraron que el número de sitios implantados fue 38(GI), 37(G2), 32(G3), y 06(G4). La reducción en el grupo IV fue como consecuencia de la alta mortalidad durante la experiencia, probablemente en función del largo tratamiento con dexametasona. Esos sitios presentaron aspectos histológicos semejantes. El análisis macroscópico de los neonatos no mostró ningún vestigio de malformación. Tampoco fueron observados abortos. El tratamiento con dexametasona por 10 días en ratas, no afecta la fertilidad y el desarrollo de los pulmones, hígado y ríñones de neonatos, mientras que la administración por 15 días lleva a una alta mortalidad materna.