Effect of Thiamine Deficiency on the Glial Fibrillary Acidic Protein ( GFAP ) Immunoreacitivity of the Astrogial Cells in Rat Forebrain

ABSTRACT

BACKGROUND: Diverse injury to central nervous system results in proliferation and hypertrophy of astrocytes. The hallmark of this response is enhanced expression of the major intermediate filament protein of astrocyte, glial fibrillary acidic protein(GFAP). These obsevations suggested that GFAP may be a useful biochemical indicator of neurotoxicity. This study is designed for investigating the chronological effects of the thiamine deficiency on the astrogrial GFAP immunoreactivity in the rat forebrain, and for comparing the difference between time-sequenital morphological changes of luxol fast blue-cresyl violet stain reported in previous study and GFAP immunoreactivity. METHODS: A total of 40 healthy Sprague-Dawley strain rats, weighing about 200gm were used as experimental animals(10 control, 30 thiamine deficient rats). Pyrithiamine was injected intraperitonially for 9 days and thiamine deficient diet was continuously supplied until sacrifice. Thiamine deficient rats were subdivided into 3 groups according to thiamine deficient state. Immunohistochemical stains for GFAP in the regions of thalamus, medial mammillary nucleus and CA1 sector in hippocampus were performed by free floating method in cell culture plate. All preperations were observed with light microscope. RESULTS: GFAP immunoactivities at thalamus were tracely positive(+) in controls, strongly positive(+++) in group I, and moderately positive(++) in group II and III. But GFAP immunoactivities at medial mammillary nucleus were tracely positive( ) in controls, moderately positive(++) in group I and III , and strongly positive(+++) in group II. At the CA1 region of hippocampus, the immunoactivities were weakly positive in controls , strongly positive(+++) in group I and II, and moderately positive(++) in group III. The diverse patterns of GFAP immunoreactivities in each vulnerable site were different from the previous morphological study. In luxol-fast and cresyl violet staining, the neuronal damage and necrosis were marked in group III, group II, and group I, in that order, which findings are consistent in all regions. CONCLUSIONS: Different patterns of time-sequential GFAP immunoactivities at each vulnerable site suggest that there are regional differences in sensitivity and resistance to thiamine deficiency.