[Alterations of glial fibrillary acidic protein in rat brain after gamma knife irradiation].
OBJECTIVE
To study glial fibrillary acidic protein (GFAP) immunoreactivity in different time and water content of the rat brain treated with gamma knife radiotherapy and to understand the alteration course of the brain lesion after a single high dose radiosurgical treatment.


METHODS
In the brains of the normal rats were irradiated by gamma knife with 160 Gy-high dose. The irradiated rats were then killed on the 1st day, 7th day, 14th day, and 28th day after radiotherapy, respectively. The positive cells of GFAP in brain tissue were detected by immunostaining; the water content of the brain tissue was measured by microgravimetry. The histological study of the irradiated brain tissue was performed with H.E. and examined under light microscope.


RESULTS
The numbers of GFAP-positive astrocytes began to increase on the 1st day after gamma knife irradiation. It was enlarged markedly in the number and size of GFAP-stained astrocytes over the irradiated areas. Up to the 28th day, circumscribed necrosis foci (4 mm in diameter) was seen in the central area of the target. In the brain tissue around the necrosis, GFAP-positive astrocytes significantly increased (P < 0.01, compared with the control group). The swelling of cells in irradiated region was observed on the 1st day; after irradiation endothelial cells degenerated and red blood cells escaped from blood vessel on the 7th day; leakage of Evans blue dye was observed in the target region on the 14th day. There was a significant decrease of specific gravity in the irradiated brain tissue the 14th and 28th day after irradiation.


CONCLUSIONS
The results suggest that GFAP can be used as a marker for the radiation-induced brain injury. The brain edema and disruption of brain-blood barrier can be occurred during the acute stage after irradiation.
Ma
Z M
ZM
Neurological Institute, Xiangya Hospital, Central South University, Changsha 410008, China.
Jiang
B
B
Ma
J R
JR
D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D015415:Biomarkers; D001921:Brain / Q000378:metabolism* / Q000473:pathology / Q000601:surgery*; D005720:Gamma Rays; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D008297:Male; D016634:Radiosurgery / Q000295:instrumentation; D051381:Rats
D015415:Biomarkers; D005904:Glial Fibrillary Acidic Protein