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Published on: August 13, 2019
17beta-estradiol attenuates hyperoxia-induced apoptosis in mouse C8-D1A cell line
Stephanie Huppmann1, Susanne Römer, Rodica Altmann
1Department of Neonatology, Charité, Campus Virchow Klinikum, Berlin, Germany. stephanie.huppmann@charite.de
Insights
Neonatal hyperoxia induces astrocyte apoptosis, but 17beta-estradiol (E2) offers significant protection. This neuroprotective effect in premature brain astrocytes is not mediated by extracellular signal-regulated kinase (ERK1/2) pathway activation.
Area of Science:
- Neuroscience
- Cell Biology
- Neonatal Medicine
Background:
- Neonatal resuscitation with oxygen can generate free radicals, linked to diseases like retinopathy of prematurity and bronchopulmonary dysplasia.
- Nonphysiologic oxygen levels induce apoptosis in the developing brain, highlighting the need for neuroprotection strategies.
- Estrogen is a known neuroprotective agent, and astrocytes play a crucial role in neuronal survival, suggesting a potential role for estrogen in protecting astrocytes.
Purpose of the Study:
- To investigate if astrocytes in cell culture are damaged by hyperoxia.
- To determine if 17beta-estradiol (E2) can protect astrocytes against hyperoxia-induced apoptosis.
- To explore the underlying mechanism of E2's potential protective effect, specifically investigating the extracellular signal-regulated kinase (ERK1/2) pathway.
Main Methods:
- Culturing C8-D1A astrocyte cells under conditions of normoxia and hyperoxia.
- Treating hyperoxic cultures with 17beta-estradiol (E2) to assess its impact on apoptosis.
- Measuring apoptosis levels and analyzing the expression of ERK1/2 and phosphorylated ERK1/2 (pERK1/2) via Western blotting.
Main Results:
- Hyperoxia significantly increased astrocyte apoptosis eightfold compared to normoxia.
- Addition of E2 reduced hyperoxia-induced apoptosis by over 50%.
- While hyperoxia increased ERK1/2 and pERK1/2 levels, preincubation with E2 decreased these levels, indicating the protective effect is not mediated by ERK1/2 up-regulation.
Conclusions:
- Hyperoxia induces apoptosis in cultured astrocytes (C8-D1A cells).
- 17beta-estradiol (E2) demonstrates a protective effect against hyperoxia-induced apoptosis in astrocytes.
- The neuroprotective mechanism of E2 in this context does not appear to involve the upregulation of the pERK1/2 pathway.
Abstract:
In premature infants, oxygen free radicals generated following neonatal resuscitation are associated with subsequent diseases such as retinopathy of prematurity and bronchopulmonary dysplasia. Recent studies in brain tissue samples have shown that nonphysiologic oxygen levels play a key role in induction of apoptosis in the developing brain. Estrogen is a well-established agent in neuroprotection and, therefore, is thought to be neuroprotective even in the premature brain. Astrocytes appear to have a critical role in protection and survival of neurons in the brain. As one of the glial cell types, they have a great potential for possible involvement in the mediation of estrogen neuroprotective effects. The aim of our study was to analyze whether astrocytes in cell cultures are damaged by hyperoxia and whether 17beta-estradiol (E2) can protect them against apoptosis. Additionally, we investigated the mechanism of the protection by E2, hypothesizing that it is mediated through extracellular signal-regulated kinase (ERK1/2). Cells underwent eightfold more apoptosis when cultivated in hyperoxia compared with normoxia. Addition of E2 reduced apoptosis in hyperoxia by more than 50%. Levels of ERK1/2 and phosphorylated ERK1/2 were increased after hyperoxia compared with normoxia. Preincubation with E2 prior to exposure to hyperoxia resulted in decreased levels of ERK1/2 and pERK1/2. Hyperoxia induces apoptosis in C8-D1A cells, and E2 seems to be a protecting factor for astrocytes in hyperoxia. This effect is not mediated through up-regulation of pERK1/2.
