ABSTRACT
The rate of cesarean section (CS) delivery has steadily increased over the past decades despite epidemiological studies reporting higher risks of neonatal morbidity and neurodevelopmental disorders. Yet, little is known about the immediate impact of CS birth on the brain, hence the need of experimental studies to evaluate brain parameters following this mode of delivery. Using the solvent clearing method iDISCO and 3D imaging technique, we report that on the day of birth, whole-brain, hippocampus, and striatum volumes are reduced in CS-delivered as compared to vaginally-born mice, with a stronger effect observed in preterm CS pups. These results stress the impact of CS delivery, at term or preterm, during parturition and at birth. In contrast, cellular activity and apoptosis are reduced in mice born by CS preterm but not term, suggesting that these early-life processes are only impacted by the combination of preterm birth and CS delivery.
Subject(s)
Brain/anatomy & histology , Cesarean Section/adverse effects , Delivery, Obstetric/adverse effects , Premature Birth , Animals , Animals, Newborn , Apoptosis , Brain Chemistry , Caspase 3/metabolism , Female , Gestational Age , Hippocampus/anatomy & histology , Hippocampus/metabolism , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Male , Mice , Neostriatum/anatomy & histology , Neostriatum/metabolism , Pregnancy , Proto-Oncogene Proteins c-fos/biosynthesis , Proto-Oncogene Proteins c-fos/metabolismABSTRACT
Neonatal hypoxia/ischemia (HI) is the most common cause of developmental neurological, cognitive and behavioral deficits in children, with hyperoxia (HHI) treatment being a clinical therapy for newborn resuscitation. Although cerebral edema is a common outcome after HI, the mechanisms leading to excessive fluid accumulation in the brain are poorly understood. Given the rigid nature of the bone-encased brain matter, knowledge of edema formation in the brain as a consequence of any injury, as well as the importance of water clearance mechanisms and water and ion homeostasis is important to our understanding of its detrimental effects. Knowledge of the pathological process underlying the appearance of dysfunctional outcomes after development of cerebral edema after neonatal HI in the developing brain and the molecular events triggered will allow a rational assessment of HHI therapy for neonatal HI and determine whether this treatment is beneficial or harmful to the developing infant.
Subject(s)
Brain Edema/etiology , Hypoxia-Ischemia, Brain/complications , Body Water , Brain/physiopathology , Homeostasis , Humans , Infant, Newborn , Oxygen Inhalation TherapyABSTRACT
Neonatal hypoxia/ischemia (HI) is a common cause of cognitive and behavioral deficits in children with hyperoxia treatment (HHI) being the current therapy for newborn resuscitation. HI induces cerebral edema that is associated with poor neurological outcomes. Our objective was to characterize cerebral edema after HI and determine the consequences of HHI (40% or 100% O(2)). Dry weight analyses showed cerebral edema 1 to 21 days after HI in the ipsilateral cortex; and 3 to 21 days after HI in the contralateral cortex. Furthermore, HI increased blood-brain barrier (BBB) permeability 1 to 7 days after HI, leading to bilateral cortical vasogenic edema. HHI failed to prevent HI-induced increase in BBB permeability and edema development. At the molecular level, HI increased ipsilateral, but not contralateral, AQP4 cortical levels at 3 and up to 21 days after HI. HHI treatment did not further affect HI-induced changes in AQP4. In addition, we observed developmental increases of AQP4 accompanied by significant reduction in water content and increase permeability of the BBB. Our results suggest that the ipsilateral HI-induced increase in AQP4 may be beneficial and that its absence in the contralateral cortex may account for edema formation after HI. Finally, we showed that HI induced impaired motor coordination 21 days after the insult and HHI did not ameliorate this behavioral outcome. We conclude that HHI treatment is effective as a resuscitating therapy, but does not ameliorate HI-induced cerebral edema and impaired motor coordination.
Subject(s)
Brain Edema/etiology , Brain Edema/therapy , Hypoxia-Ischemia, Brain/complications , Hypoxia-Ischemia, Brain/therapy , Oxygen Inhalation Therapy/methods , Resuscitation/methods , Animals , Animals, Newborn , Aquaporin 4/metabolism , Blood-Brain Barrier/metabolism , Body Water , Brain/metabolism , Brain Edema/metabolism , Capillary Permeability , Disease Models, Animal , Dyskinesias/complications , Dyskinesias/metabolism , Dyskinesias/therapy , Functional Laterality , Hypoxia-Ischemia, Brain/metabolism , Random Allocation , Rats , Rats, Wistar , Time FactorsABSTRACT
Analysis of apoptosis in brain tissue following ischemia, hypoxia, or oxidative stress has technical limitations. The use of counting cells displaying apoptotic morphology is time intensive, vulnerable to sampling errors, and suffers from low numbers of total recorded events. Other cell death assays such as agarose gel analysis of DNA fragmentation, TUNEL, or ELISA are time intensive, limited to a single endpoint measure, and can be technically difficult to perform or reproduce. To overcome these limitations, we set out to develop a technique using flow cytometry to measure apoptosis based on the physical properties of light scatter produced from isolated nuclei. This dye/marker free approach would bypass many of the inherent encumbrances and reproducibility problems found in other apoptosis assays. Here we demonstrate that this new technique, using flow cytometry performed on isolated nuclei, allows rapid quantitation of apoptosis in a variety of brain tissues without the need for intercalating dyes or fluorescent markers. We conclude that this technique significantly improves currently available protocols to quantify apoptosis from tissue and offers the possibility to perform additional analysis on the same population of nuclei via downstream assays.
