Efectos del tratamiento con vitamina E en el tubo neural y médula espinal en embriones y fetos de ratones Mus musculus expuestos al uso de ácido valproico / Effects of treatment with vitamin E in the neural tube and spinal cord Mus musculus mouse embryos exposed to the use of valproic acid

El ácido valproico (VPA) es el principal anticonvulsivante utilizado contra la epilepsia durante la gestación. Sin embargo, en etapas iniciales del embarazo actúa como teratógeno y ocasiona malformaciones como fisura labio-palatina, alteraciones en el desarrollo genital y espina bífida, siendo esta última la más frecuente. Esto se produce debido al aumento de especies reactivas de oxígeno, pudiendo contrarrestarse administrando vitamina E. El objetivo fue determinar si la vitamina E disminuye el daño en tubo neural y médula espinal de embriones y fetos de ratonas expuestas a VPA. Se conformaron 8 grupos de animales. A los 8 días post-fecundación se les administró a los grupos 1 y 5 suero fisiológico 0,3 mL; grupos 2 y 6 VPA 600 mg/Kg; grupos 3 y 7 VPA 600 mg/Kg y vitamina E 200 UI/Kg; grupos 4 y 8 vitamina E 200 UI/kg. A los 12 días post-fecundación, se sacrificaron los grupos 1, 2, 3 y 4, y a los 17 días los restantes grupos. Los embriones fueron procesados y teñidos con cresil violeta, observándose cortes histológicos a nivel cervical, torácico y lumbar. Los grupos tratados con vitamina E presentaron menor cantidad de neuroblastos y motoneuronas, pero de tamaño mayor en comparación al grupo tratado con VPA (p<0,05), siendo similares a los grupos controles. Al comparar el tubo neural y médula espinal en los distintos niveles (cervical, torácico y lumbar), no hubo diferencias estadísticamente significativas. La administración prenatal de vitamina E disminuye los defectos en tubo neural y médula espinal de embriones de 12 y 17 días de gestación sometidos a VPA.

Valproic Acid (VPA) is the main anticonvulsant used for epilepsy throughout the gestation period. However, when used at early stages of pregnancy, it acts as a tetarogenic agent, causing congenital malformations such as cleft-lip and/or cleft palate, abnormal genital development and spina bifida, being the latter the most frequent. This is the result of the increase of reactive oxygen species, which can be countered with the supplementation of vitamin E. The aim was determine if vitamin E minimizes the damage to the neural tube and spinal cord of mice embryos and fetuses previously exposed to VPA. Eight groups of mice were constituted. Eight days post fertilization, groups 1 and 5 were administered 0,3 ml of saline solution; groups 2 and 6 600mg/Kg of VPA, groups 3 and 7 600mg/Kg of VPA and 200UI/Kg of Vitamin E; groups 4 and 8 200 UI/Kg of Vitamin E. 12 days after fertilization, groups 1, 2, 3 and 4 were euthanized, whereas in the case of the remaining groups, the same process was performed 17 days after fertilization. The embryos were stained with cresyl violet, thus enabling the observation of histological sections at cervical, thoracic and lumbar levels. Groups supplied with vitamin E presented a lower amount of neuroblasts and motoneurons. However, these elements were bigger in size compared to the group treated with VPA (p<0,05), being these results similar to those obtained with the control groups. When comparing the neural tube and spinal cord at different levels (cervical, thoracic and lumbar), no statistically significant differences were found. It was determined that prenatal administration of vitamin E lessens the damage to the neural tube and spinal cord of mice embryos of 12 and 17 days of gestation previously exposed to VPA.

Consumo de fumonisinas y daños a la salud humana / Fumonisin intake and human health

Las fumonisinas son una familia de micotoxinas que contaminan al maíz, alteran el metabolismo de los esfingolípidos y del folato, se asocian con defectos del tubo neural y están catalogadas por la Agencia Internacional de Investigación en Cáncer (IARC por sus siglas en inglés) como posibles carcinógenos humanos. Debido a que en México los derivados de maíz constituyen una parte importante de la dieta y existe alta prevalencia de población genéticamente susceptible a la deficiencia de folato, en este ensayo se presentan las evidencias mundiales y nacionales de la exposición a fumonisinas y la relevancia que para México representa la evaluación de esta exposición.

Fumonisins are mycotoxins that contaminate maize, disrupt the folate and sphingolipid metabolism, are associated with neural tube defects, and are considered by the International Agency for Research on Cancer (IARC) as possible human carcinogens. Since maize-based foods are significant components of the Mexican diet and there is a high prevalence of genetic susceptibility for folate deficiency among Mexicans, this essay presents international and national evidence of fumonisin exposure and the relevance that such exposure represents for Mexico.

The effects of high dose progesterone on neural tube development in early chick embryos.

BACKGROUND: Although folic acid deficiency is known to be one of the factors in the development of spina bifida and other neural tube defects (NTD) the exact pathophysiology still remains unclear. Progesterone is an endogenous hormone which increases significantly during pregnancy. AIMS: We aimed to study the possible negative effects of high dose progesterone on neural tube development in early chick embryos. In order to test our hypothesis, early chick embryos were exposed to physiological saline, normal and high doses of progesterone. SETTINGS AND DESIGN: 160 fertile, specific pathogen free white leghorn eggs (Gallus gallus), all at stage eight of development were divided into four equal groups. MATERIALS AND METHODS: The first group was incubated without any operation. The second group was injected with physiological saline. The third and fourth groups were injected with two and twenty times more than physiologic doses of progesterone respectively. After 48 hours of incubation, all embryos were analyzed for the presence of NTDs under light microscopy. STATISTICAL ANALYSIS USED: None. RESULTS: At 48 hours of incubation, 84% (135/160) of the embryos passed characteristics of Stage 12 development and were included to the study. None of the eggs in the first three groups showed NTDs, whereas 81.8% (27/33) of the eggs in the fourth group showed NTDs. CONCLUSIONS: Our study showed that progesterone at levels twenty times more than its physiologic level might cause NTDs. Further studies are needed to explain the mechanisms of this teratogenic effect.

Fetal exencephaly arising as a result of preimplantation exposure to ammonium chloride.

OBJECTIVES: To investigate the effect of preimplantation exposure to 0.6 mM ammonium chloride on both preimplantation and postimplantation development of (F1 x F1) strain mouse embryos. METHOD: Two-cell stage mouse embryos were randomly allocated to culture in either M16 medium or M16 added with 0.6 mM ammonium chloride for 2 days before being transferred to 2.5 day pseudopregnant recipients. Embryo morphology was assessed after 1 and 2 days of culture. The recipient females were sacrificed on day 15.5 of gestation. The number of implantation sites, fetuses, moles and any gross abnormalities found were noted. RESULTS: There was no significant difference in the number of embryos reaching morula stage after two days of culture between the two groups (chi2=0.86, P>0.05). Implantation and pregnancy loss rates between the two groups were within comparable ranges. Crown-rump length was significantly higher in the group of embryos exposed to ammonium chloride (t=2.46, P<0.05). There was one gross abnormality, exencephaly, detected in the experimental group (4.35% per fetus obtained). CONCLUSIONS: Besides the abnormal increase in fetal size, preimplantation exposure to ammonium chloride also resulted in gross abnormality, exencephaly. If such effects occurred in the course of human in vitro fertilization, it could be devastating. Further study in this aspect is, therefore, clinically very important in preventing unwanted abnormalities that could arise from human in vitro fertilization.

Antiepilépticos, ácido fólico y embarazo / Antiepileptic drugs, folate and pregnancy

Existen numerosas complicaciones en pacientes embarazadas portadoras de epilepsia, ya sea por los efectos del embarazo sobre las crisis, complicaciones del parto y puerperio, y además de las malformaciones congénitas. Más del 90 por ciento de mujeres con epilepsia, quienes reciben drogas antiepilépticas (DAES), podrán tener su hijo sin ningún tipo de defectos al nacimiento y los estudios han demostrado que entre el 6-8 por ciento de recién nacidos,cuyas madres recibían anticonvulsivantes, presentaban algún tipo de alteración. Estudios epidemiológicos y experimentales demuestran fuerte evidencia de los efectos teratogénicos de las DAES se ha involucrado al Acido Fólico (AF) como uno de los factores para la producción de malformaciones congénitas. Evidenciándose disminución de los niveles del AF en embarazadas y más aún en aquellas que reciben DAES. Debido a esto y a que en niños con malformaciones del tubo neural sus madres presentaban AF disminuido en sangre, se usó AF en un estudio multicéntrico, comprobándose una disminución del riesgo de malformaciones del tubo neural en un 72 por ciento en el grupo que injirió AF en relación al control. Basándose en este estudio y sin tener evidencias en pacientes epilépticos que reciben DAES se recomienda administrar 4 mg de AF 4 semanas antes y durante el primer trimestre del embarazo,conjuntamente con educación y manejo multidisciplinario de su embarazo

Aspirin by virtue of its acidic property may act as teratogen in early chick embryo.

Aspirin (acetylsalicyclic acid) was dissolved either in normal saline or in phosphate buffer and was used in two doses to find out whether teratogenic potential of aspirin in chick blastoderm model is due to its acidic property or due to drug action. Drug was injected sub-blastodermally by window technique in fresh embryonated eggs after 17 hours of incubation at 39 degrees C. Eggs were re-incubated and harvested at 40 hours. Normal development of embryos was seen with normal saline and percentage of normal embryos with 30 micrograms (pH-3.19) and 120 micrograms (pH-2.64) aspirin was 31.7 and 4.9 respectively. Buffer produced 80.8% normal embryos and buffered 30 micrograms (pH-6.87) and 120 micrograms (pH-6.69) aspirin produced 67.7% and 30.8% normal embryos respectively. Changing the pH of aspirin to near neutral decreased the defect induced by aspirin but a significant effect of aspirin was observed at higher dose which could be independent of pH action.

Mechanism of aspirin induced neural tube defect in chick embryo.

The effect of acetyl salicylic acid (aspirin) on neural tube development in chick embryo was studied, using the chick embryo blastoderm model. Aspirin was injected in four different doses sub-blastodermally into fresh embryonated eggs. The role of PGE1 and PGE2 alpha in the defect induced by aspirin on neural tube development in chick embryo was studied. PGE1 (5 micrograms) given after aspirin (30 micrograms) treatment was found to produce greater defect in development. All the four doses of aspirin used (i.e., 6, 30, 60 and 120 micrograms/embryo) produced significant changes (P < 0.01) in the neural tube development of chick embryo. Pre-treatment with PGE1 did not modify the defect induced by aspirin, whereas pre-treatment with PGF2 alpha prevented neural tube defects induced by aspirin. It appears that aspirin (in the doses used) affects neural tube formation by decreasing PGF2 alpha synthesis in chick embryo blastoderm.

Experimental exencephaly and myeloschisis in rats

To elucidate the early sequential morphogenetic progress of exencephaly and myeloschisis, rat embryos whose mothers had been treated with hypervitaminosis A were studied at 1-day interval from gestation day 10.5 to 15.5. In exposed animals sequential change was found in both exencephaly and myeloschisis as the embryos grew up. The 10.5-day old exencephalic embryos had still widely open cephalic neural tubes. Exencephalic embryos older than 13.5 days of gestation showed strikingly severe eversion and overgrowth of the cephalic neuroepithelium, thus failed in forming normal primitive brain. The convex dorsal surface of the exencephaly was covered with ependyma, which was connected directly with surrounding surface eqithelium at the periphery. The earliest morphologically recognized myeloschisis was in the 13.5-day old embryos. In myeloschisis, divergence at the roof plate and eversion of the spinal neural tube, disorganized overgrowth of the neuroepithelium, malformed and misplaced spinal ganglia and nerve roots, and absence of the neural arch and dermal covering were characteristic. It is suggested that exencephaly results from failure of the cephalic neural tube closure which is followed by eversion and overgrowth of the neuroepithelium. And failure in closure of the posterior neuropore and disturbance in the development of the tail bud probably play major role in the morphogenesis of myeloschisis.