Dexamethasone therapy of triethyltin induced cerebral edema

Stimulation of astrocytes affects cytotoxic brain edema

Cytotoxic brain edema has been produced in rats by subacute intoxication with triethyltin (TET). Some animals were allowed to recover spontaneously, others were post-treated with an extract of Ginkgo biloba (EGB) for 1 to 4 weeks, beginning 3 days after intoxication was stopped. The time course of the resolution of the edema was studied biochemically and morphologically by light microscopy, histochemistry and electron microscopy (EM). Morphometric evaluation showed that the spontaneous reabsorption of TET-induced edema was very slow: it was evident only 2 weeks after ending TET administration and it required more than 4 weeks to be completed. EGB therapy markedly decreased the vacuolation, as well as the abnormal levels of water and sodium contents, 1 week after beginning the treatment. Less influence of EGB was observed at the later stages. During spontaneous recovery, astroglial cells in the edematous white matter of TET-intoxicated animals showed short and swollen processes containing few organelles, low levels of NADH- and NADPH-tetrazolium reductase activities and glial fibrillary acidic protein (GFAP)-immunofluorescence for about 2 weeks. During EGB therapy the astrocytes regained their cellular processes, containing intense oxidative enzyme activities and GFAP-immunofluorescence as early as after 1 week of treatment. In the EM, astrocytes often appeared hypertrophic, surrounding myelin vacuoles and displaying phagocytosis of myelin debris. We conclude that EGB can accelerate the reabsorption of TET-induced cerebral edema and improve the astroglial reaction.

Effect of an extract of Ginkgo biloba on triethyltin-induced cerebral edema

The effect of an extract of Ginkgo biloba was studied on cerebral edema in rats intoxicated with triethyltin chloride (TET). Brains of TET-treated rats showed elevated water and sodium levels and a significant increase in the sodium/potassium ratio. Animals treated with TET plus the extract did not show water and electrolyte changes. The course of intoxication and treatment was studied light- and electron-microscopically. A severe edema with extensive vacuolization was seen in the cerebral and cerebellar white matter. Morphometric measurements revealed a significant decrease in these manifestations of the cytotoxic edema when the animals were treated with an extract of Ginkgo biloba. Thus, we conclude that this extract has a protective effect on the development of a cytotoxic edema in the white matter of the brain.

Effects of steroids on behavior, electrophysiology, water content and intracranial pressure in cerebral cytotoxic edema

The effect of therapy with methylprednisolone sodium succinate (5.33 mg/kg/day) and dexamethasone sodium phosphate (1 mg/kg/day) on grey matter of rabbits rendered edematous by a metabolic blocker, 6-aminonicotinamide, is presented. Methylprednisolone was observed to significantly reduce the water content of the grey matter (p less than 0.001), whereas dexamethasone had little effect. Both agents, however, were equally effective in reducing intracranial pressure (p less than 0.001) and improving intracranial elastance, when compared to untreated animals. However, in the dexamethasone-treated group, there was improved behavior and EEG findings in 50% of the animals when compared to the untreated controls, and similar improvement was present in less than 15% of the methylprednisolone group. The disparity between the effects on water content, behavior and EEG supports the thesis that in cerebral edema these agents have a metabolic effect out of proportion to their effect on tissue water.