Increase in TNF alpha transport after SCI is specific for time, region, and type of lesion

The dynamic changes of the blood-brain barrier and blood-spinal cord barrie r (BBB) are an important part of the CNS response to injury. This study add resses the permeability of the BBB in the acute phase of spinal cord injury (SCI) to the thoracic region. SCI by compression or by complete transectio n was generated in mice. BBB disruption was evaluated by spinal cord uptake of radiolabeled albumin. The BBB of the thoracic spinal cord was disrupted immediately aft compression injury, lasting for 2 days. This was followed by a delayed permeability increase in the cervical spinal cord beginning 3 days after injury. After transection, BBB disruption was limited to the tho racic spinal cord and was present only immediately postinjury. The entry of TNF alpha not only was increased at the time of BBB disruption, following the same pattern, but also had secondary changes after the BBB permeability to albumin had returned to normal. The increase of TNF alpha entry, best e xplained by upregulation of the specific transport system for TNF alpha, wa s pronounced in the lumbar spinal cord as well as the thoracic region, and followed a different time course after the two types of injury. Integrating our results with those of the literature regarding the roles of inflammato ry responses and the effects of TNF alpha in spinal cord regeneration, we c onclude that the time-, region-, and lesion-specificity of the upregulation of TNF alpha transport is part of the regulatory changes at the BBB in res ponse to SCI. (C) 2001 Academic Press.