Glycerol does not reduce neuronal damage in experimental Streptococcus pneumoniae meningitis in rabbits

To study the effect of high-dose glycerol therapy on inflammation and neuronal destruction in a model of experimental pneumococcal meningitis, 14 New Zealand White rabbits were infected intracisternally with Streptococcus pneumoniae type 3. Sixteen hours after infection, 7 animals received intravenous glycerol therapy (1 g kg(-1) bolus and 0.5 g kg (1)h(-1) maintenance dose) and 7 animals served as untreated controls.After 8 h of therapy, the glycerol CSF:serum ratio exceeded the previously observed values in rabbits with an intact blood-CSF barrier (0.72+/-0.25 vs. 0.35), i.e. glycerol crossed the blood-CSF barrier more readily in animals altered by meningitis than in healthy animals. In contrast, the brain tissue:serum ratio of glycerol (grey matter 0.33+/-0.29, white matter 0.30+/-0.31) was substantially lower than the CSF:serum ratio (p=0.03 and p=0.047). There was no significant effect of glycerol on intracranial pressure, brain water content and neuron-specific enolase release into the CSF. Glycerol significantly increased the density of neuronal apoptosis in the dentate gyrus of the hippocampal formation. Therefore, glycerol does not appear to be beneficial in experimental pneumococcal meningitis.