Kovalchuk Y. P., Ushakova G. A., Znanetska O. М.

Oles Honchar Dnipropetrovsk National University


Neuroglia is auxiliary but important component of central nervous system which is combined with neurons genetically, morphologically and functionally. It is a complex of cellular elements that carries out basic, trophic, secretory and protective functions. Experimental results confirm the active participation of glial cells in the key functions of nervous system.

The structure of glial cells includes such proteins as S-100b protein and glial fibrillary acid protein (GFAP).

Protein S-100b is considered as one of main molecular components of the intracellular systems providing a functional homeostasis of brain cells by a combination and integration of various metabolic processes. It is one of the first specific proteins of CNS that was found by Mur, S-100b is a marker of brain damage (cortical, ischemic, etc.) metabolic disorders in the brain due to the impact of various factors on the organism which is investigated. It is significant that experimental effect to S-100b protein usually isn’t accompanied by noticeable alteration of animals somatic condition, but at the same time it leads to various violations of integrative function of the brain, information homeostasis in providing and optimization of that its function is defined. S-100b protein localization as specific protein of nervous system has been a subject of numerous researches. S-100b protein was found in CNS and PNS of all vertebrata and some invertebrate animals. Mainly it is concentrated in a neuroglia (85-90%), a significant amount of it is in astrocytes, in neurons (no more than 10-15%), in olyhodendrotsytes its quantity is insignificant. Messes and other authors have investigated the intensity of biosynthesis of S-100b protein in the process of ontogeny of humans and animals. It`s turned out that S-100b protein appears at 10-15 week in a brain of an embryo of humans in different areas of the brain: cerebellum, pans average and midbrain spinal cord, etc. At about the 30th week there is an accumulation of   S-100b protein in all the areas of CNS, except a frontal lobe where the increase of protein content coincides with the emergence of bioelectric activity of the brain.

The glial fibrillary acid protein (GFAP) is a histospecific component of the intermediate filament (IF) of astrocytes cytoskeleton. GFAP as a part of PF plays an important role in movement modulation of astrocytes and providing stable morphology of their shoots during astrogliosis development. GFAP is a specific marker of astrocytes and takes part in the formation of cytoskeleton of cells glial filament, takes part in molecular mechanisms neuron – astrocytes interactions. It is a highly specific protein of a brain which isn't found outside of CNS. It has been shown that GFAP very quickly releases in blood after traumatic injury of the brain (can be used as a marker of damage and predictive factor concerning the result), but multiple traumas can be without GFAP release. In CNS after damage astrocytes correspond for astrogliosis. Astrogliosis is characterized by fast synthesis of GFAP. It is known that the level of GFAP usually increases with aging. Thanks to high specificity and early release from CNS after traumatic injury of the brain, GFAP can be a very useful marker for early diagnostics. Astrocytes reactivity in the brain of gerbils during aging has been the purpose of our work.

12 gerbils were divided into two groups (n = 6): 1 – control one as for age, adults (8 months) with a standard diet, 2 – old (2 years) animals with a standard diet. At the end of experiment the animals were decapitated under mild anesthesia, the brain was isolated from and divided into three parts: cerebellum, thalamus and hippocampus, which are subsequently used to obtain cytosolic and cytoskeleton fractions proteins. The concentration of GFAP and S-100b protein was determined by solid-phase competitive ELISA. Statistical analysis of the results was performed using SPSS 10.0 for Windows, the difference was considered significant at p <0.05.

The experimental data show a stable level of filament GFAP in the thalamus of gerbils aged 6 months and 2 years. In adult animals, the protein content was 2mkg/ml, and the old ones 1.8 mkg/ml. In the hippocampus and cerebellum of experimental animals the significant increase in the level of GFAP was determined in old gerbils compared with adults, indicating the development of reactive astrogliosic in these structures during the aging. We observed that in adult animals it was 1.1 mkg/ml, and the old ones 2.2 mkg/ml. For S-100b protein, the experimental data show a stable level in the thalamus and cerebellum of gerbils aged 6 months and 2 years. In the hippocampus of experimental animals the significant increase in S-100b protein in old gerbils (2,1 ± 0,6 mg / ml) was determined compared with adult ones (0,6 ± 0,09 mg / ml), indicating the development of reactive astrogliosis in the hippocampus.

The analisis of the data obtained indicates a lack of probable changes in protein metabolism in astrocytes thalamus of old gerbils, but simultaneously it is established that the development of astrogliosis in the hippocampus and cerebellum can lead to disruption of integrative brain function and information homeostasis. The indicated brain areas play an important role securing and optimizing these functions.