[The distribution of glial fibrillary acidic protein and protein S-100 in experimental brain tumors in rats].

The methods of quantitative immunoelectrophoresis and indirect immunofluorescence were used study the content of glial fibrillary acid protein in 10 serially reinoculated rat gliomas induced primarily by ethylnitrosourea (a total of 135 tumors). It was found that the GFAP content reduced with increase of malignancy. However, wide scattering of the GFAP content in some of the tumors was characteristic of all strains. In the group of slowly growing glial tumors (2 malignant astrocytomas and one malignant oligoastrocytoma) the GFAP content ranged from 50 to 600% and exceeded the normal content two-to threefold on the average. In the group of highly malignant gliomas (4 malignant ependymomas, 2 malignant gliomas, and one glioblastoma) the GFAP content was within the limits of 65-120%. In most cases the GFAP level was below normal or could not be determined at all. At the same time, tumors with a high GFAP content were encountered. The GFAP-positive cells were unevenly distributed in the gliomas: separately, in foci, and around the vessels. Their number increased in the direction of the periphery of the tumor. Intensive fluorescence was noted on the tumor--brain borderline. The content of protein S-100 in the experimental gliomas was always below normal.