Dynamics of alaninaminotransferase activity in subcellular fractions of different areas of brain cortex and hypothalamus in postnatal ontogenesis under protein-free feeding regime and after its withdrawal

Total and specific activities of alaninaminotransferase (Al-AT) were determined in general tissues, mitochondrial and cytosol fractions of visual, orbital, motor, limbic areas of brain cortex and hypothalamus of three-month old and one-year old rats under 10-20 days and 30 days protein deprivation and under recovery of normal food regime during the same terms. It was found out that Al-AT activities under impairment of feeding regime depend on several factors including morphofunctional peculiarities of the brain structure, terms of protein-free feeding, studied cellular substrates and animal age. On the basis of the experimental data the possible ways of enzyme involvement in the processes of biochemical adaptation occurring in the brain in nutritional protein deficiency were analyzed. The adaptive enzyme functions within the cell compartments are directed toward accomplishment of complex compensatory and adaptive reactions. On the level of mitochondrial fractions, the enzyme is involved into the complex of compensatory reactions via glucose-alanin cycle to support neurons with energetic substrates. In cytosol, the enzyme adaptive functions lie in maintaining of structural and synaptic cell plasticity on account of transamination reaction. The mentioned mechanism, according to the experimental results, is move developed in three-month old animals than in one-year ones.