Developmental exposure to pesticides that disrupt retinoic acid signaling causes persistent retinoid and behavioral dysfunction in zebrafish.

Early developmental exposure to environmental toxicants may play a role in the risk for developing autism. A variety of pesticides have direct effects on retinoic acid (RA) signaling and as RA signaling has important roles in neurodevelopment, such compounds may cause developmental neurotoxicity through an overlapping adverse outcome pathway. It is hypothesized that a pesticide's embryonic effects on retinoid function may correspond with neurobehavioral disruption later in development. In the current studies, we determined the effects of RA-acting pesticides on neurobehavioral development in zebrafish. Buprofezin and imazalil caused generalized hypoactivity in the larval motility test, whereas chlorothalonil and endosulfan I led to selective hypoactivity and hyperactivity, respectively. With buprofezin, chlorothalonil, and imazalil, hypoactivity and/or novel anxiety-like behaviors persisted in adulthood and buprofezin additionally decreased social attraction responses in adulthood. Endosulfan I did not produce significant adult behavioral effects. Using qPCR analyses of adult brain tissue, we observed treatment-induced alterations in RA synthesis or catabolic genes, indicating persistent changes in RA homeostasis. These changes were compound-specific, with respect to expression directionality, and potential patterns of homeostatic disruption. Results suggest the likely persistence of disruptions in RA signaling well into adulthood and may represent compensatory mechanisms following early life stage exposures. This study demonstrates that early developmental exposure to environmental toxicants that interfere with RA signaling causes short as well as long-term behavioral disruption in a well-established zebrafish behavioral model and expand upon the meaning of the RA adverse outcome pathway, indicating that observed effects likely correspond with the nature of underlying homeostatic effects.

Protective effect of quercetin on histomorphometric changes in kidney of retinoid acid-treated rat fetuses / Efecto protector de la quercetina sobre los cambios histomorfométricos en el riñón de fetos de rata tratados con ácido retinoico

SUMMARY: Retinoic acid, an active metabolite of vitamin A, plays essential signaling roles in mammalian embryogenesis. Prenatal rat fetuse exposure to retinoid induces some malformations in various organs, the most active and teratogenic metablolite is all-transretinoic acid (atRA). The teratogenic effects of some drugs can be prevented by the application of antioxidant drugs and stimulation of the maternal immune system. Also, quercetin, a naturally occurring flavonoid has excellent antioxidant properties. Therefore, the aim of this study was assess the protective effects of quercetin against atRA in fetuses of rat's kidney tissue. This study was performed on 40 pregnant rats that were divided into seven groups. Control group received normal saline and test groups received DMSO, quercetin (75 mg/kg), quercetin (200 mg/kg), atRA (25 mg/kg), atRA (25 mg/kg) plus quercetin (75 mg/kg) and atRA (25 mg/kg) plus quercetin (200 mg/kg), intraperitoneally at 8-10th days of gestation. Fetuses were collected at 20th day of gestation. Kidneys were collected and placed in 10 % buffered formalin solution. Then, kidneys were sectioned by routine method and stained by H&E and examined histologically. On histomorphomertrical examination, it was observed the priglomerular space and diameter of renal corpuscle in group which received only atRA were significantly (p≤0.05) greater than those received normal saline, dimethyl sulfoxide and quercetin, while these two indexes in group which received atRA plus quercetin significantly (p≤0.05) decreased by quercetin as dose dependent manner. Number of renal corpuscles were significantly (p≤0.05) decreased by atRA, but the quercetin could not affect the glomerular numbers. It is concluded that quercetin can protect fetuses against atRA damages and prevent their incidence probably via its antioxidant effect.

RESUMEN: El ácido retinoico, un metabolito activo de la vitamina A, desempeña un papel esencial de señalización en la embriogénesis de mamíferos. La exposición al ácido retinoico en fetos de ratas prenatales induce malformaciones en varios órganos, siendo el metabolito más activo y teratogénico el ácido transretinoico (ATRA). Los efectos teratogénicos de algunos medicamentos se pueden prevenir mediante la aplicación de medicamentos antioxidantes y la estimulación del sistema inmune materno. Además, la quercetina, un flavonoide de origen natural, tiene excelentes propiedades antioxidantes. Por lo tanto, el objetivo de este estudio fue evaluar los efectos protectores de quercetina contra ATRA en fetos de tejido de riñón de rata. Este estudio se realizó en 40 ratas preñadas que se dividieron en siete grupos. El grupo control recibió solución salina normal y los grupos de prueba recibieron DMSO, quercetina (75 mg / kg), quercetina (200 mg / kg), ATRA (25 mg / kg), ATRA (25 mg / kg) más quercetina (75 mg / kg) y ATRA (25 mg / kg) más quercetina (200 mg / kg), por vía intraperitoneal a los 8-10 días de gestación. Los fetos se recolectaron a los 20 días de gestación. Los riñones se recogieron y se colocaron en solución de formalina tamponada al 10 %. Luego, los riñones se seccionaron por método de rutina y se tiñeron con H & E y se examinaron histológicamente. En el examen histomorfométrico, se observó que el espacio periglomerular y el diámetro del corpúsculo renal en el grupo que recibió solo ATRA fueron significativamente (p≤0.05) mayores que los que recibieron solución salina normal, dimetilsulfóxido y quercetina, mientras que estos dos índices, en el grupo que recibió ATRA más quercetina, disminuyó significativamente (p≤0.05) en forma dependiente de la dosis. El número de corpúsculos renales disminuyó significativamente (p≤0.05) por el ATRA, pero la quercetina no pudo afectar el número de glomérulos. Se concluye que la quercetina puede proteger a los fetos contra daños de ATRA y prevenir su incidencia, probablemente, a través de su efecto antioxidante.

Teratogenic effect of retinoic acid in swiss mice

PURPOSE: To identify the types of malformations resulting from the administration of retinoic acid (RA) to Swiss mice on different days of pregnancy. METHODS: Twenty-four pregnant Swiss mice were divided into 4 groups of 6 animals each. The experimental groups received a single intraperitoneal injection of RA (70 mg/kg) on gestational days 7, 8 and 9 (D7, D8 and D9), while control animals (C) received only saline solution. RESULTS: Were obtained: exencephaly (C:0; D7:16.1 percent; D8:25.4 percent; D9:0), myelomeningocele (C:0; D7:25.8 percent, D8:30.9 percent, D9:0), spina bifida occulta (C:0, D7:29 percent, D8:41.8 percent, D90), gastroschisis (C:0, D7:6.4 percent D8:5.4 percent, D9:0), omphalocele (C:0, D7:6.4 percent, D8:14.5 percent, D9:0), lower limb alterations (C:0, D7:74.1 percent, D8:80 percent, D9:0), imperforated anus (C:0, D7:100 percent, D8:100 percent, D9:100 percent), and tail agenesis/alteration (C: D7:100 percent, D8:100 percent, D9:100 percent). CONCLUSION: The experimental model using Swiss mice proved to be efficient in the induction of the different types of defects, with the eighth gestational day being the one that most favored the induction of neural tube defect, omphalocele, gastroschisis, lower limb defects, imperforated anus and tail agenesis/alteration. On this basis, this is a useful model for future investigation of neural development and of the formation of the appendicular skeleton.

OBJETIVO: Identificar os tipos de malformação resultantes da administração do ácido retinóico (AR) a camundongos Swiss em diferentes dias gestacionais. MÉTODOS: Foram utilizados 24 camundongos fêmeas, linhagem Swiss, prenhes, divididos em 4 grupos com 6 animais cada. Os grupos experimentais receberam uma única injeção intraperitoneal de AR (70mg/Kg) nos dias gestacionais 7, 8 e 9 (D7, D8 e D9), enquanto que os animais do grupo controle (C) receberam apenas solução salina. RESULTADOS: Foram encontrados: exencefalia (C:0; D7:16.1 por cento; D8:25.4 por cento; D9:0); mielomeningocele (C:0; D7:25.8 por cento; D8:30.9 por cento; D9:0); Espina Bífida Oculta (C:0; D7:29 por cento; D8:41.8 por cento; D90); gastrosquise (C:0; D7:6.4 por cento D8:5.4 por cento; D9:0); onfalocele (C:0; D7:6.4 por cento; D8:14.5 por cento; D9:0); alterações do membro inferior (C:0; D7:74.1 por cento; D8:80 por cento; D9:0); imperfuração anal (C:0; D7:100 por cento; D8:100 por cento; D9:100 por cento) e agenesia/alteração de cauda (C: D7:100 por cento; D8:100 por cento; D9:100 por cento). CONCLUSÕES: O modelo experimental utilizando camundongo Swiss mostrou-se eficiente na indução dos diferentes tipos de defeitos, sendo o oitavo dia gestacional o mais propicio na indução de DFTN, onfalocele, gastrosquise, defeitos de membro inferior, imperfuração anal e agenesia/alteração de cauda, tornando este um modelo útil para futuras investigações do desenvolvimento neural e no processo de formação do esqueleto apendicular.