Fetal growth restriction (FGR) is a common complication of pregnancy, principally caused by suboptimal placental function, and is associated with high rates of perinatal mortality and morbidity. Clinical studies suggest that the time of onset of placental insufficiency is an important contributor towards the neurodevelopmental impairments that are evident in children who had FGR. It is however currently unknown how early-onset and late-onset FGR differentially affect brain development. The aim of this study was to examine neuropathology in early-onset and late-onset FGR fetal sheep and to determine whether they differentially alter brain development. We induced placental insufficiency and FGR via single umbilical artery ligation at either 88 days (early-onset) or 105 days (late-onset) of fetal sheep gestation (term is approx. 147 days), reflecting a period of rapid white matter brain development. Fetal blood samples were collected for the first 10 days after surgery, and all fetuses were sacrificed at 125 days' gestation for brain collection and subsequent histopathology. Our results show that early-onset FGR fetuses became progressively hypoxic over the first 10 days after onset of placental insufficiency, whereas late-onset FGR fetuses were significantly hypoxic compared to controls from day 1 after onset of placental insufficiency (SaO₂ 46.7 ± 7.4 vs. 65.7 ± 3.9%, respectively, p = 0.03). Compared to control brains, early-onset FGR brains showed widespread white matter injury, with a reduction in both CNPase-positive and MBP-positive density of staining in the periventricular white matter (PVWM), subcortical white matter, intragyral white matter (IGWM), subventricular zone (SVZ), and external capsule (p < 0.05 for all). Total oligodendrocyte lineage cell counts (Olig-2-positive) did not differ across groups, but mature oligodendrocytes (MBP-positive) were reduced, and neuroinflammation was evident in early-onset FGR brains with reactive astrogliosis (GFAP-positive) in the IGWM and cortex (p < 0.05), together with an increased number of Iba-1-positive activated microglia in the PVWM, SVZ, and cortex (p < 0.05). Late-onset FGR was associated with a widespread reduction of CNPase-positive myelin expression (p < 0.05) and a reduced number of mature oligodendrocytes in all white matter regions examined (p < 0.05). NeuN-positive neuronal cell counts in the cortex were not different across groups; however, the morphology of neuronal cells was different in response to placental insufficiency, most notable in the early-onset FGR fetuses, but it was late-onset FGR that induced caspase-3-positive apoptosis within the cortex. This study demonstrates that early-onset FGR is associated with more widespread white matter injury and neuroinflammation; however, both early- and late-onset FGR are associated with complex patterns of white and grey matter injury. These results indicate that it is the timing of the onset of fetal compromise relative to brain development that principally mediates altered ...

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To elucidate the impact of maternal seizures in the developing rat brain, pregnant Wistar rats were subjected to the pilocarpine-induced seizures and pups from different litters were studied at different ages. In the first 24 h of life, blood glucose and blood gases were analyzed. (14)C-leucine [(14)C-Leu] incorporation was used to analyze protein synthesis at PN1, and Western Blot method was used to analyze protein levels of Bax, Bcl-2 and Poly(ADP-ribose) polymerase-1 (PARP-1) in the hippocampus (PN3-PN21). During the first 22 days of postnatal life, body weight gain, length, skull measures, tooth eruption, eye opening and righting reflex have been assessed. Pups from naive mothers were used as controls. Experimental pups showed a compensated metabolic acidosis and hyperglycemia. At PN1, the [(14)C-Leu] incorporation into different studied areas of experimental pups was lower than in the control pups. During development, the protein levels of Bax, Bcl-2 and PARP-1 in the hippocampus of experimental pups were altered when compared with control pups. A decreased level of pro- and anti-apoptotic proteins was verified in the early postnatal age (PN3), and an increased level of pro-apoptotic proteins concomitant with a reduced level of anti-apoptotic protein was observed at the later stages of the development (PN21). Experimental pups had a delay in postnatal growth and development beyond disturb in protein synthesis and some protein expression during development. These changes can be result from hormonal alterations linked to stress and/or hypoxic events caused by maternal epileptic seizures during pregnancy.

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