L-Arginine and Superoxide Dismutase Prevent or Reverse Cerebral Hypoperfusion after Fluid-Percussion Traumatic Brain Injury

Abstract

To determine whether treatment with L-arginine or superoxide dismutase (SOD) would prove effective in reducing cerebral hypoperfusion after traumatic brain injury (TBI), we measured cerebral blood flow (CBF) using laser Doppler flowmetry (LDF) in rats treated before or after moderate (2.2 atm) fluid-percussion (FP) TBI. Rats were anesthetized with isoflurane and prepared for midline FP TBI and then for LDF by thinning the calvaria using an air-cooled drill. Rats were then randomly assigned to receive sham injury, sham injury plus L-arginine (100 mg/kg, 5 min after sham TBI), TBI plus 0.9% NaCl, TBI plus L-arginine (100 mg/kg, 5 min post-TBI), TBI plus SOD (24,000 U/kg pre-TBI + 1600 units/kg/min for 15 min after TBI), or TBI plus SOD and L-arginine. A second group of rats received TBI plus saline, L-, or D-arginine (100 mg/kg, 5 min after-TBI). After treatment and TBI or sham injury, CBF was measured continuously using LDF for 2 h and CBF was expressed as a percent of the preinjury baseline for 2 h after TBI. Rats treated with saline or D-arginine exhibited significant reductions in CBF that persisted throughout the monitoring period. Rats treated with L-arginine alone or in combination with SOD exhibited no decreases in CBF after TBI. CBF in the SOD-treated group decreased significantly within 15 min after TBI but returned to baseline levels by 45 min after TBI. These studies indicate that L-arginine but not D-arginine administered after TBI prevents posttraumatic hypoperfusion and that pretreatment with SOD will restore CBF after a brief period of hypoperfusion.

Detection of Structural and Metabolic Changes in Traumatically Injured Hippocampus by Quantitative Differential Proteomics

“…Peptides with charge > 3, false-discovery rate > 3%, 18 O: 16 O ratios < 0.1 or > 10, and reversed sequences, were removed from further analysis. Calculated peptide ratios were log 2 transformed and mean centered prior to statistical analysis.…”

“…4,16,18 Rectal and temporalis muscle temperatures were monitored throughout the surgery. Sham-injured rats were connected to the fluid percussion trauma device without injury.…”

“…Briefly, the paired experimental peptide samples were resuspended in normal water (H 2 16 O) for sham, or heavy water (H 2 18 O) for TBI, containing ammonium bicarbonate and immobilized trypsin. The corresponding 18 O-labeled and 16 O-unlabeled samples were pooled, dried, and desalted.…”

“…The zoom scan data were used to calculate the relative abundance ratios of 18 O-labeled peptide/ 16 O-unlabeled peptide pairs using MassXplorer. 57 We used power spectrum transformation to remove high-frequency noise and contributions from co-eluting species, to determine the elemental composition of the sequences to compute theoretical isotopic distributions for determination of peak positions, and for curve fitting to calculate the ratios.…”

“…Differential stable isotope labeling was performed on tryptic peptides from TBI samples labeled with 18 O-water, while peptides from control samples contained normal 16 O. Using our recently developed spectral analysis program for quantification of 18 O: 16 O peptide ratios, MassXplorer, 57 we quantified expression of 38,135 peptide ratios (Supplemental Table S1; see online supplementary material at http://www.liebertonline. com).…”