Non-Targeted Metabolic Profiling of Cerebellum in Spina Bifida Fetal Rats

Spina bifida, known more commonly as myelomeningocele, is a neural tube defect that results in herniation of the cerebellum through the foramen magnum into the central canal as part of the Chiari II malformation. Effects stemming from the herniated cerebellum and its metabolic profile have not been extensively studied. The objective of this study is to examine the metabolic effects of this disease on the cerebellum in utero through the utilization of a retinoid acid-induced Spina bifida rat model. Analysis of this model at mid-late (day 15) and term (day 20) of gestation in comparison to both non-exposed and retinoic acid-exposed non-myelomeningocele controls, the observed metabolic changes suggest that mechanisms of oxidative stress and energy depletion are at play in this neuro tissue. These notable mechanisms are likely to result in further damage to neural tissue as the fetus grows and the compressed cerebellum develops and herniates more due to myelomeningocele.

High resolution three-dimensional imaging and measurement of lung, heart, liver, and diaphragmatic development in the fetal rat based on micro-computed tomography (micro-CT)

Understanding of normal fetal organ development is crucial for the evaluation of the pathogenesis of congenital anomalies. Various techniques have been used to generate imaging of fetal rat organogenesis, such as histological dissection with 3-dimensional reconstruction and scanning electron microscopy. However, these techniques did not imply quantitative measurements of developing organs (volumes, surface areas of organs). Furthermore, a partial or total destruction of the embryos prior to analysis was inevitable. Recently, micro-computed tomography (micro-CT) has been established as a novel tool to investigate embryonic development in non-dissected embryos of rodents. In this study, we used the micro-CT technique to generate 4D datasets of rat embryos aged between embryonic day 15-22 and newborns. Lungs, hearts, diaphragms, and livers were digitally segmented in order to measure organ volumes and analyze organ development as well as generate high-resolution 3D images. These data provide objective values compiling a 4D atlas of pulmonary, cardiac, diaphragmatic, and hepatic development in the fetal rat.

Dexmedetomidine mitigates isoflurane-induced neurodegeneration in fetal rats during the second trimester of pregnancy

Dexmedetomidine has significant neuroprotective effects. However, whether its protective effects can reduce neurotoxicity caused by isoflurane in fetal brain during the second trimester of pregnancy remains unclear. In this study, timed-pregnancy rats at gestational day 14 spontaneously inhaled 1.5% isoflurane for 4 hours, and were intraperitoneally injected with dexmedetomidine at dosages of 5, 10, 20, and 20 μg/kg 15 minutes before inhalation and after inhalation for 2 hours. Our results demonstrate that 4 hours after inhaling isoflurane, 20 μg/kg dexmedetomidine visibly mitigated isoflurane-induced neuronal apoptosis, reversed downregulation of brain-derived neurotrophic factor expression, and lessened decreased spatial learning and memory ability in adulthood in the fetal rats. Altogether, these findings indicate that dexmedetomidine can reduce neurodegeneration induced by isoflurane in fetal rats during the second trimester of pregnancy. Further, brain-derived neurotrophic factor participates in this process.

Zinc protection in fetal rats for maternal mercury exposure-induced growth retardation is probably associated with S100B expression

AIM

The study was conducted to investigate the effects of maternal mercury exposure on fetal rat development and zinc protection in mercury-exposed rats.

METHODS

Pregnant rats were subjected to zinc sulfate pre-feeding, mercury exposure and zinc sulfate co-feeding. The control rats were administered distilled water. On day 19, the placental weight, overall weight, size and tail length of fetal rats, mercury content and S100B level in the placenta were determined using Western blot analysis.

RESULTS

Compared with the control, mercury exposure at 2.0 mg/kg.d significantly reduced placental weight and fetal development, resulting in reduced fetal weight, size and tail length, while zinc pre-feeding increased placental weight and other fetal developmental parameters. Compared with mercury exposure, co-feeding with zinc significantly reduced mercury-induced injury in the fetal rats. S100B and mercury content levels were significantly elevated in rats maternally exposed to methylmercury chloride, compared with the unexposed control, while co-feeding with methylmercury chloride and zinc sulfate significantly reduced S100B and mercury levels in the placenta.

CONCLUSION

Maternal exposure to mercury results in increased S100B in the placenta. Zinc sulfate feeding could reduce S100B and mercury levels, thereby protecting the rats from mercury damage. S100B level may be used to measure the antagonism between zinc and mercury during pregnancy.