Caspase activation in fetal rat brain following experimental intrauterine inflammation

Brain Res. 2008 Mar 20:1200:138-45. doi: 10.1016/j.brainres.2008.01.045. Epub 2008 Jan 26.

Abstract

Intrauterine inflammation has been implicated in developmental brain injuries, including the development of periventricular leukomalacia (PVL) and cerebral palsy (CP). Previous studies in our rat model of intrauterine inflammation demonstrated apoptotic cell death in fetal brains within the first 5 days after lipopolysaccharide (LPS) administration to mothers and eventual dysmyelination. Cysteine-containing, aspartate-specific proteases, or caspases, are proteins involved with apoptosis through both intracellular (intrinsic pathway) and extracellular (extrinsic pathway) mechanisms. We hypothesized that cell death in our model would occur mainly via activation of the extrinsic pathway. We further hypothesized that Fas, a member of the tumor necrosis factor receptor (TNFR) superfamily, would be increased and the death inducing signaling complex (DISC) would be detectable. Pregnant rats were injected intracervically with LPS at E15 and immunoblotting, immunohistochemical and immunoprecipitation analyses were performed. The presence of the activated form of the effector caspase (caspase-3) was observed 24 h after LPS administration. Caspase activity assays demonstrated rapid increases in (i) caspases-9 and -10 within 1 h, (ii) caspase-8 at 2 h and (iii) caspase-3 at 4 h. At 24 h after LPS, activated caspase-3(+)/Fas(+) cells were observed within the developing white matter. Lastly, the DISC complex (caspase-8, Fas and Fas-associated death domain (FADD)) was observed within 30 min by immunoprecipitation. Apoptosis in our model occurs via both extrinsic and intrinsic pathways, and activation of Fas may play a role. Understanding the mechanisms of cell death in models of intrauterine inflammation may affect development of future strategies to mitigate these injuries in children.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Caspases / metabolism*
  • Cerebral Palsy / enzymology
  • Cerebral Palsy / etiology
  • Cerebral Palsy / physiopathology
  • Death Domain Receptor Signaling Adaptor Proteins / metabolism
  • Disease Models, Animal
  • Encephalitis / chemically induced
  • Encephalitis / enzymology*
  • Encephalitis / pathology
  • Enzyme Activation
  • Fas-Associated Death Domain Protein / metabolism
  • Female
  • Fetal Diseases / chemically induced
  • Fetal Diseases / enzymology*
  • Fetal Diseases / pathology
  • Humans
  • Infant, Newborn
  • Inflammation Mediators
  • Isoenzymes / metabolism
  • Leukomalacia, Periventricular / enzymology
  • Leukomalacia, Periventricular / etiology
  • Leukomalacia, Periventricular / physiopathology
  • Lipopolysaccharides
  • Nerve Degeneration / chemically induced
  • Nerve Degeneration / enzymology*
  • Nerve Degeneration / etiology
  • Pregnancy
  • Rats
  • Signal Transduction
  • fas Receptor / metabolism*

Substances

  • Death Domain Receptor Signaling Adaptor Proteins
  • Fas-Associated Death Domain Protein
  • Inflammation Mediators
  • Isoenzymes
  • Lipopolysaccharides
  • fas Receptor
  • Caspases