Hypoxic-Ischemic Encephalopathy and Premature Babies Brain Damage: Impact of Estetrol

Neonatal hypoxic-ischemic brain injury remains a main problem of perinatal medicine. About 20% of affected newborns die in the postnatal period, and an additional 25% will sustain childhood disabilities mostly in the form of motor and cognitive delays. The nature of the deficits is dependent on the gestational age and severity of the insult, though it is s seldom reported in preterm infants. No medical treatment provides important neuroprotection against HIE. Studies in animal models of HIE may provide important information for the development of treatment for this pathological condition.
Estetrol (E4) is a recently described estrogen with four hydroxyl-groups that is synthesized exclusively during pregnancy by the human fetal liver. In this study, we defined the antioxidative effect of E4 in primary hippocampal cell cultures taken from newborn rat pups (in vitro) and evaluated its neuroprotective and therapeutic potency in neonatal HIE model of the immature newborn rat (in vivo). Lactate Dehydrogenase (LDH) and cell survival (MTS) assays were performed on primary neuronal cell cultures. Rat pups body temperatures were examined along with their body and brain weights. Brains were studied at the level of the hippocampus and cortex. Intact cell counting and expressions of markers for neuronal cell viability (microtubule-associated protein-2 (MAP-2)), neurogenesis (doublecortin (DCX)) and angiogenesis (vascular-endothelial growth factor (VEGF)) were evaluated by histo- and immunohistochemistry. The serum levels of two markers of brain damage (S100B and glial fibrillary acidic protein (GFAP)) were measured by ELISA.
Our results demonstrate that E4 has a significant neuroprotective and therapeutic dose-dependent effects. Estetrol has powerful antioxidative and cell survival effects in vitro. It decreases the early gray matter loss and promotes neuro- and angiogenesis in vivo. Estetrol treatment has no effects on body weight, brain weight or body temperature. Taken together, Estetrol might become an important safe and physiological substance to treat neonatal HIE.