Upregulation of cystathionine β-synthase and p70S6K/S6 in neonatal hypoxic ischemic brain injury

Brain Pathol. 2017 Jul;27(4):449-458. doi: 10.1111/bpa.12421. Epub 2016 Aug 28.


Encephalopathy of prematurity (EOP) is a complex form of cerebral injury that occurs in the setting of hypoxia-ischemia (HI) in premature infants. Using a rat model of EOP, we investigated whether neonatal HI of the brain may alter the expression of cystathionine β-synthase (CBS) and the components of the mammalian target of rapamycin (mTOR) signaling. We performed unilateral carotid ligation and induced HI (UCL/HI) in Long-Evans rats at P6 and found increased CBS expression in white matter (i.e. corpus callosum, cingulum bundle and external capsule) as early as 24 h (P7) postprocedure. CBS remained elevated through P21, and, to a lesser extent, at P40. The mTOR downstream target 70 kDa ribosomal protein S6 kinase (p70S6K and phospho-p70S6K) and 40S ribosomal protein S6 (S6 and phospho-S6) were also overexpressed at the same time points in the UCL/HI rats compared to healthy controls. Overexpression of mTOR components was not observed in rats treated with the mTOR inhibitor everolimus. Behavioral assays performed on young rats (postnatal day 35-37) following UCL/HI at P6 indicated impaired preference for social novelty, a behavior relevant to autism spectrum disorder, and hyperactivity. Everolimus restored behavioral patterns to those observed in healthy controls. A gait analysis has shown that motor deficits in the hind paws of UCL/HI rats were also significantly reduced by everolimus. Our results suggest that neonatal HI brain injury may inflict long-term damage by upregulation of CBS and mTOR signaling. We propose this cascade as a possible new molecular target for EOP-a still untreatable cause of autism, hyperactivity and cerebral palsy.

Keywords: CBS; autism; brain injury; hypoxia; mTOR; prematurity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Antigens, CD / metabolism
  • Antigens, Differentiation, Myelomonocytic / metabolism
  • Choice Behavior / physiology
  • Cystathionine beta-Synthase / genetics
  • Cystathionine beta-Synthase / metabolism*
  • Disease Models, Animal
  • Everolimus / therapeutic use
  • Exploratory Behavior / physiology
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Developmental / physiology
  • Glial Fibrillary Acidic Protein / metabolism
  • Hypoxia-Ischemia, Brain / metabolism*
  • Hypoxia-Ischemia, Brain / pathology
  • Hypoxia-Ischemia, Brain / physiopathology*
  • Immunosuppressive Agents / therapeutic use
  • Locomotion
  • Oligodendrocyte Transcription Factor 2 / metabolism
  • Rats
  • Rats, Long-Evans
  • Ribosomal Protein S6 Kinases / genetics
  • Ribosomal Protein S6 Kinases / metabolism*
  • Ribosomal Protein S6 Kinases, 70-kDa / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism*
  • Up-Regulation / drug effects
  • Up-Regulation / physiology*
  • White Matter / metabolism
  • White Matter / pathology


  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • CD68 antigen, human
  • Glial Fibrillary Acidic Protein
  • Immunosuppressive Agents
  • Oligodendrocyte Transcription Factor 2
  • Everolimus
  • Ribosomal Protein S6 Kinases
  • Ribosomal Protein S6 Kinases, 70-kDa
  • Cystathionine beta-Synthase