Dying neurons in thalamus of asphyxiated term newborns and rats are autophagic

Authors

  • Vanessa Ginet PhD,

    1. Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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  • Marie P. Pittet MD,

    1. Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
    2. Clinic of Neonatology, Department of Pediatrics, University Hospital Center, Lausanne, Switzerland
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  • Coralie Rummel,

    1. Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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  • Maria Chiara Osterheld MD,

    1. Institute of Pathology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
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  • Reto Meuli MD, PhD,

    1. Department of Diagnostic and Interventional Radiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
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  • Peter G. H. Clarke PhD,

    1. Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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  • Julien Puyal PhD,

    1. Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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  • Anita C. Truttmann MD

    Corresponding author
    1. Clinic of Neonatology, Department of Pediatrics, University Hospital Center, Lausanne, Switzerland
    • Address correspondence to Dr Truttmann, Clinic of Neonatology, University Hospital Center and University of Lausanne, Department of Pediatrics and Pediatric Surgery, Avenue Pierre Decker, Maternité, Lausanne, Vaud, Switzerland 1011. E-mail: anita.truttmann@chuv.ch

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  • V. Gine and M. P. Pittet contributed equally to this article.

  • Share senior authorship.

Abstract

Objective

Neonatal hypoxic–ischemic encephalopathy (HIE) still carries a high burden by its mortality and long-term neurological morbidity in survivors. Apart from hypothermia, there is no acknowledged therapy for HIE, reflecting the lack of mechanistic understanding of its pathophysiology. (Macro)autophagy, a physiological intracellular process of lysosomal degradation, has been proposed to be excessively activated in excitotoxic conditions such as HIE. The present study examines whether neuronal autophagy in the thalamus of asphyxiated human newborns or P7 rats is enhanced and related to neuronal death processes.

Methods

Neuronal autophagy and cell death were evaluated in the thalamus (frequently injured in severe HIE) of both human newborns who died after severe HIE (n = 5) and P7 hypoxic–ischemic rats (Rice–Vannuci model). Autophagic (LC3, p62), lysosomal (LAMP1, cathepsins), and cell death (TUNEL, caspase-3) markers were studied by immunohistochemistry in human and rat brain sections, and by additional methods in rats (immunoblotting, histochemistry, and electron microscopy).

Results

Following severe perinatal asphyxia in both humans and rats, thalamic neurons displayed up to 10-fold (p < 0.001) higher numbers of autophagosomes and lysosomes, implying an enhanced autophagic flux. The highly autophagic neurons presented strong features of apoptosis. These findings were confirmed and elucidated in more detail in rats.

Interpretation

These results show for the first time that autophagy is enhanced in severe HIE in dying thalamic neurons of human newborns, as in rats. Experimental neuroprotective strategies targeting autophagy could thus be a promising lead to follow for the development of future therapeutic approaches. Ann Neurol 2014;76:695–711

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