Chapter

Brain Edema XII

Volume 86 of the series Acta Neurochirurgica Supplements pp 257-260

Neuropeptide release influences brain edema formation after diffuse traumatic brain injury

  • Robert VinkAffiliated withDepartment of Pathology, The University of AdelaideDepartment of Neuroscience, Georgetown University Email author 
  • , A. YoungAffiliated withSchool of Pharmacy and Molecular Sciences, James Cook University
  • , C. J. BennettAffiliated withSchool of Pharmacy and Molecular Sciences, James Cook University
  • , X. HuAffiliated withSchool of Pharmacy and Molecular Sciences, James Cook University
  • , C. O. ConnorAffiliated withDepartment of Pathology, The University of Adelaide
  • , I. CernakAffiliated withDepartment of Neuroscience, Georgetown University
  • , A. J. NimmoAffiliated withSchool of Pharmacy and Molecular Sciences, James Cook University

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Abstract

The mechanisms associated with edema formation after traumatic brain injury (TBI) have not been fully elucidated. In peripheral tissue injury, the neurogenic component of inflammation plays a significant role in increased vascular permeability and edema formation. However, few studies have examined the role of neuropeptide induced neurogenic inflammation following TBI. Adult male Sprague-Dawley rats were either left untreated, or pre-treated with capsaicin (125 mg/kg s.c.) or equal volume vehicle, and injured 14 days later using the 2-meter impact-acceleration model. Subgroups of animals were assessed for blood brain barrier (BBB) permeability (Evans Blue), brain edema (wet weight/dry weight) and functional outcome (Barnes maze and Rotarod) for up to 2 weeks post-trauma. Increased BBB permeability was present in untreated animals between 3 and 6 h after injury but not at later time-points. Edema was maximal at 5 h after trauma, declined and then significantly increased over the 5 days post-trauma. In contrast, capsaicin pre-treated, neuropeptide-depleted animals exhibited no significant increase in BBB permeability or edema compared to vehicle treated animals after injury. Notably, motor and cognitive impairments were significantly reduced in the capsaicin-pretreated animals. We conclude that neurogenic inflammation contributes to the development of edema and posttraumatic deficits after diffuse TBI.

Keywords

Neurotrauma edema neuropeptides capsaicin outcome inflammation neurogenic