28
Effects of Ionizing Radiation and Aluminum Chloride
on Protein of Glial Intermediate Filaments
in the Rat Brain
V. S. Nedzvetskii,
1
P. A. Nerush,
2
A. A. Tikhomirov,
1
and L. A. Romanenko
2
Neirofiziologiya/Neurophysiology, Vol. 33, No. 1, pp. 33-38, January-February, 2001.
Received January 21, 2000.
We studied the effects of irradiation with X-rays (the total dose of 0.0129 C/kg was attained over 7, 14, or 21 days),
increased entry of Al
3+
into the organism (0.2% AlCl
3
in drinking water), and the combined influence of these
factors for 21 days on the contents of the soluble and filamentous forms of glial fibrillary acidic protein (GFAP) in
the tissues of the hippocampus, cerebellum, and neocortex of albino rats. After irradiation for 7 days, a clear trend
toward drops in the GFAP contents in the structures under study was observed, while irradiation in the same dose,
but for 14 or 21 days, resulted in increases in the contents of both GFAP forms (within a range of 13-29%, as
compared with the control). Entry of aluminum chloride with water also resulted in an increase in the GFAP
contents in all studied structures; changes in the filamentous form were more intensive. The combined influence of
irradiation and Al
3+
resulted in more intensive shifts in the GFAP levels; the content of its filamentous form
increased in all structures by about 50%, while shifts of the soluble form were somewhat smaller.
Keywords: glial fibrillary acidic protein (GFAP), cytoskeleton, intermediate filaments, salts of aluminum,
small doses of ionizing irradiation.
1
2
Dnepropetrovsk National University, Ukraine.
Dnepropetrovsk State Medical Academy, Ukraine.
Neurophysiology, Vol. 33, No. 1, 2001
0090-2977/01/3301-0028$25.00 © 2001 Plenum Publishing Corporation
INTRODUCTION
Proteins which are specific for nerve and glial cells
play a considerable role in the functioning of the ner-
vous system. Neurospecific proteins (NSP) are intensely
involved in such fundamental processes in the neural
tissues as synaptogenesis, synaptic transmission, axon
transport, and a number of other events. The cytoskele-
ton is an important structural component of the cells of
the nervous system. It includes microfilaments, inter-
mediate filaments, and microtubules. A normal state of
the cytoskeleton is a necessary condition for adequate
functioning of the above-mentioned cells.
The specificity of structural proteins correspond-
ing to the cell histotype is a significant feature of the
intermediate filaments. In the axons and dendrites of
brain neurons, proteins of the cytoskeleton are repre-
sented by a triplet of a neurofilamentous proteins (mo-
lecular mass, 70, 160, and 210 kdalton). In astrocytes,
the intermediate filaments are to a considerable extent
built from glial fibrillary acidic protein (GFAP, 49 kdal-
ton) [1]. It is supposed that these proteins determine
functional heterogeneity and specificity of the cyto-
skeleton of glial cells and neurons under normal condi-
tions and play an important role in the development of
neurodegenerative processes. For example, disturbances
in the structure of intermediate filaments is one of the
morphophysiological and biochemical manifestations of
Alzheimers disease, parkinsonian syndrome, amyo-
trophic lateral sclerosis, etc. [2, 4].
Various chemical and physical factors are capable
of influencing the cytoskeleton of the cells of the ner-
vous system. Earlier, we studied the effects of lethal
and small doses of ionizing radiation on the intermedi-
ate filaments and observed that irradiation causes sig-
nificant modifications in the GFAP content and also
modifies the polypeptide composition of the soluble