Effect of dexamethasone on serum protein extravasation in experimental brain infarcts of monkey: an immunohistochemical study.

Experimental brain infarcts were produced in 12 adult baboons (Papio cynocephalus) by transorbital permanent clipping of the left middle cerebral artery. One group (seven monkeys) received daily injections of 1 mg/kg dexamethasone, starting 1 h after vascular occlusion and continuing till the end of the experiment. Another group (five monkeys) was not treated. One week after vascular occlusion the volume of infarcts and peri-infarct edema was estimated morphometrically on histological sections, using Masson's trichrome stain and the peroxidase-anti-peroxidase (PAP) technique for visualization of serum protein extravasation. In the untreated animals the average volume of infarct was 6.57 +/- 4.23% (mean +/- SD) and the volume of edema 7.83 +/- 2.93% of ipsilateral hemisphere. In the treated animals the infarct volume was not different (7.95 +/- 3.00%), but the volume of peri-infarct edema was significantly lower (2.82 +/- 3.06%, p less than 0.05). The results obtained indicate that dexamethasone treatment reduces the development of peri-infarct edema but does not influence the size of infarcts.