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 ± 1.0mmHg) and white blood cell (WBC) count in the cerebrospinal fluid (CSF)(2,709 ± 482cells/μl) 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%and78.82 ± 0.05%,resp.), ICP (7.7 ± 1.1mmHg and4.9 ± 0.8mmHg, resp.) and CSF WBC count (1,257 ± 168cells/μl an976 ± 105cells/μl, resp.). However, methylprednisolone did not inhibit the increae of rCBF (163.5 ± 13.7%and160.9 ± 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, bu thad no effect on microvascular changes during the early phase of experimental pneumococcal meningitis.