Effects of Traumatic Brain Injury on Regional Cerebral Blood Flow in Rats as Measured with Radiolabeled Microspheres

Abstract

To clarify the effect of experimental brain injury on regional CBF (rCBF), repeated rCBF measurements were performed using radiolabeled microspheres in rats Subjected to fluid-percussion traumatic brain injury. Three consecutive microsphere injections in six uninjured control rats substantiated that the procedure induces no significant changes in hemodynamic variables or rCBF. Animals were subjected to left parietal fluid-percussion brain injury of moderate severity (2.1–2.4 atm) and rCBF values were determined (a) prior to injury and 15 min and 1 h following injury (n = 7); and (b) prior to injury and 30 min and 2 h following injury (n = 7). At 15 min post injury, there was a profound reduction of rCBF in all brain regions studied (p < 0.01). Although rCBF in the hindbrain had recovered to near-normal by 30 min post injury, rCBF in both injured and contralateral (uninjured) forebrain areas remained significantly suppressed up to 1 h post injury. At 2 h post injury, recovery of rCBF to near-normal values was observed in all brain regions except the focal area of injury (left parietal cortex) where rCBF remained significantly depressed (p < 0.01). This prolonged focal oligemia at the injury site was associated with the development of reproducible cystic necrosis in the left parietotemporal cortex at 4 weeks post injury. Our results demonstrate that acute changes in rCBF occur following experimental traumatic brain injury in rats and that rCBF remains significantly depressed up to 2 h post injury in the area circumscribing the trauma site.

Hippocampal CA3Lesion Prevents Postconcussive Metabolic Dysfunction in CA1

“…Re duction of CBF can have a significant effect on the lumped constant when 2DG is used to determine glucose metabolism (Ginsberg and Reivich, 1979;Nakai et aI., 1988). Two studies have reported that CBF is reduced following a more severe F-P injury than that conducted in the current study (Yuan et aI., 1988;Yamakami and McIntosh, 1989). With use of the microsphere method, these studies reported that the injury-induced reduction in CBF lasts for -60 min, with levels in a few studies reaching 41 J Cereb Blood Flow Metab, Vol.…”

Characterization of the Effects of Adenosine Receptor Agonists on Cerebral Blood Flow in Uninjured and Traumatically Injured Rat Brain using Continuous Arterial Spin-Labeled Magnetic Resonance Imaging

“…Multivariate analysis also revealed an effect of time after injury on CBF. Most investigators have reported an initial reduction in CBF, followed by progressive recovery after experimental TBI (Yamakami and McIntosh, 1989;Kochanek et al, 1995). In saline-treated rats in this study, after severe CCI, CBF recovered by B5% to 50% between B3.5 and B5 h in ROIs beneath the impact site.…”

Long-lasting protection in brain trauma by endotoxin preconditioning

“…Notably, we as well as earlier studies addressing preconditioning in TBI (Perez-Pinzon et al, 1999;Shein et al, 2007Shein et al, , 2008Umschwief et al, 2010) have been using models of cerebral contusions in which a core lesion is surrounded by an area (traumatic penumbra) of reduced cerebral blood flow (Assaf et al, 1999;Kochanek et al, 2002;Yamakami and McIntosh, 1989). We do not know whether the target of preconditioning neuroprotection after TBI is the area around the contusion characterized by reduced cerebral blood flow and thus similarly to ischemic tissue.…”