Sex-dependent mitophagy and neuronal death following rat neonatal hypoxia-ischemia

T G Demarest; E L Waite; T Kristian; A C Puche; J Waddell; M C McKenna; G Fiskum

doi:10.1016/j.neuroscience.2016.08.026

Sex-dependent mitophagy and neuronal death following rat neonatal hypoxia-ischemia

Neuroscience. 2016 Oct 29:335:103-13. doi: 10.1016/j.neuroscience.2016.08.026. Epub 2016 Aug 21.

Authors

T G Demarest¹, E L Waite², T Kristian³, A C Puche⁴, J Waddell⁵, M C McKenna⁶, G Fiskum⁷

Affiliations

¹ Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), University of Maryland School of Medicine, Baltimore, MD 21201, USA; Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
² Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 21201, USA.
³ Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), University of Maryland School of Medicine, Baltimore, MD 21201, USA; Veterans Affairs Medical Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁴ Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁵ Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁶ Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁷ Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (S.T.A.R.), University of Maryland School of Medicine, Baltimore, MD 21201, USA; Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: gfiskum@anes.umm.edu.

Abstract

Males are more susceptible than females to long-term cognitive deficits following neonatal hypoxic-ischemic encephalopathy (HIE). Mitochondrial dysfunction is implicated in the pathophysiology of cerebral hypoxia-ischemia (HI), but the influence of sex on mitochondrial quality control (MQC) after HI is unknown. Therefore, we tested the hypothesis that mitophagy is sexually dimorphic and neuroprotective 20-24h following the Rice-Vannucci model of rat neonatal HI at postnatal day 7 (PN7). Mitochondrial and lysosomal morphology and degree of co-localization were determined by immunofluorescence in the cerebral cortex. No difference in mitochondrial abundance was detected in the cortex after HI. However, net mitochondrial fission increased in both hemispheres of female brain, but was most extensive in the ipsilateral hemisphere of male brain following HI. Basal autophagy, assessed by immunoblot for the autophagosome marker LC3BI/II, was greater in males suggesting less intrinsic reserve capacity for autophagy following HI. Autophagosome formation, lysosome size, and TOM20/LAMP2 co-localization were increased in the contralateral hemisphere following HI in female, but not male brain. An accumulation of ubiquitinated mitochondrial protein was observed in male, but not female brain following HI. Moreover, neuronal cell death with NeuN/TUNEL co-staining occurred in both hemispheres of male brain, but only in the ipsilateral hemisphere of female brain after HI. In summary, mitophagy induction and neuronal cell death are sex dependent following HI. The deficit in elimination of damaged/dysfunctional mitochondria in the male brain following HI may contribute to male vulnerability to neuronal death and long-term neurobehavioral deficits following HIE.

Keywords: cell death; lysosome; mitochondria; mitophagy; morphology; sex-dependent.

MeSH terms

Animals
Animals, Newborn
Brain / physiopathology*
Disease Models, Animal
Female
Hypoxia-Ischemia, Brain / physiopathology*
Male
Mitochondria*
Mitophagy / physiology*
Neurons
Rats, Sprague-Dawley

Grants and funding

I01 BX000917/BX/BLRD VA/United States