Methylprednisolone attenuates inflammation, increase of brain water content and intracranial pressure, but does not influence cerebral blood flow changes in experimental pneumococcal meningitis

Abstract

We investigated the effect of methylprednisolone on pathophysiological alterations in experimental pneumococcal meningitis. Untreated rats injected with pneumococcal cell wall components after hydrolization with M1 muramidase (PCW-M) developed an increase of regional cerebral blood flow (rCBF; 165.0 +/- 12.8%, baseline 100%, mean +/- S.E.M.), brain water content (79.23 +/- 0.10%), intracranial pressure (ICP; 11.9 +/- 1.0 mmHg) and white blood cell (WBC) count in the cerebrospinal fluid (CSF) (2,709 +/- 482 cells/microliters) within 8 h after intracisternal (i.c.) challenge. Pretreatment with methylprednisolone or administration of methylprednisolone 4 h after i.c. challenge significantly attenuated the increase of brain water content (78.88 +/- 0.08% and 78.82 +/- 0.05%, resp.), ICP (7.7 +/- 1.1 mmHg and 4.9 +/- 0.8 mmHg, resp.) and CSF WBC count (1,257 +/- 168 cells/microliters and 976 +/- 105 cells/microliters, resp.). However, methylprednisolone did not inhibit the increase of rCBF (163.5 +/- 13.7% and 160.9 +/- 6.8%, resp.), whereas dexamethasone significantly attenuated microvascular changes. Hypercapnia-induced reactivity of cerebral vessels tested 8 h after i.c. injection was preserved in all groups. In conclusion, we found that methylprednisolone significantly attenuated the increase of brain water content, ICP and CSF WBC count, but had no effect on microvascular changes during the early phase of experimental pneumococcal meningitis.