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O-216 Melatonine Reduces Bbb Breakdown In A Rat Model Of Neonatal Excitotoxic Damage
  1. A Zanin1,
  2. R Moretti2,
  3. J Pansiot2,
  4. D Spiri2,
  5. L Manganozzi2,
  6. I Kratze3,
  7. G Favero4,
  8. A Vasiljevic3,
  9. VE Rinaldi2,
  10. I Pic2,
  11. D Massano2,
  12. I D’Agostino2,
  13. MR La Rocca2,
  14. L Rodella4,
  15. R Rezzani4,
  16. J Ek5,
  17. N Strazielle3,
  18. JF Ghersi-Egea3,
  19. P Gressens2,
  20. L Titomanlio2
  1. 1Neonatal Intensive Care Unit, Robert Debre Hospital, Paris, France
  2. 2INSERM UMR-676, Robert Debre Hospital, Paris, France
  3. 3Inserm U1028 CNRS UMR5292, Lyon Neurosciences Research Center, Lyon, France
  4. 4Department of Clinical and Experimental Sciences, Section of Anatomy and Physiopathology, Brescia, Italy
  5. 5Perinatal Center Dept Neuroscience and Physiology, Gothenburg University, Gothenburg, Sweden

Abstract

Objective The Blood-brain barrier (BBB) is a complex structure that protects the central nervous system (CNS) extracellular fluid from peripheral insults. Understanding the molecular basis and functioning of the BBB has a significant potential for future strategies to prevent and treat neurological disorders. The aim of our study was (1) to investigate BBB alterations in an excitotoxic model and (2) to test the protective properties of melatonin.

Methods The glutamate analogue ibotenate was injected intracerebrally in postnatal day 5 (P5) rat pups to mimic excitotoxic injury. Rats were sacrificed at P5+2 h, P5+4 h, P5+18 h. Lesion size and location of tight junction (TJ) proteins were determined by immunohistochemistry and BBB leakage after ibotenate injection by dextran staining. BBB proteins gene expression (TJs efflux transporters and detoxification enzymes) was determined on cortex and plexus. A group of pups was treated with melatonin (5 mg/kg, intraperitoneal).

Results Dextran extravasation was found 2 h after the insult, suggesting a rapid BBB breakdown that resolved at +4 h. A significant reduction in extravasation was observed in melatonin-treated pups. Molecular Biology, immunohistochemistry and electron microscopy showed a dynamic BBB modification during the first 4 h, partially reversed with melatonin. Lesion size evaluation confirmed melatonin white matter neuroprotection.

Interpretation Our study, for the first time, evaluates the BBB at a very early time point, and it demonstrates that excitotoxicity causes early BBB disruption and that at this phase melatonin neuroprotects by preventing TJ proteins modifications, before acting as an anti-inflammatory and antioxidant molecule, and promoting axonal regrowth.

Abstract O-216 Figure 1

A quantitative analysis of lesion size in cortical plate and white matter induced by ic injection of ibotenate (ibo) in the presence or in the absence of ip melatonin injection 5 mg/kg

Abstract O-216 Figure 2

B, C Cresyl-violet stained sections showing brain lesions induced by ibotenate ic injected on P5 rat pups and studied at the age of P10. (B: PBS ip injection, C:5 mg/kg melatonin ip injection)

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