Levels of Free Amino Acids and their Derivatives in the Brain Cortex of Rats During Unilateral Ischemia

Abstract

The efficiency of treatment of ischemic brain damage depends upon integrity of sofisticated conceptions of its pathogenesis. One of the prospective approaches in the development of most comprehensive treatment can be the study of the pool of free amino acids (AAs) as a possible target for the correction in such pathology. Available information does not provide a complete view on the changes of their content under ischemia of various severity. The aim of the study was to evaluate changes in the content of free amino acids and their derivatives in the frontal cortex of the cerebral hemispheres of rats at different terms of unilateral ischemia. Materials and methods: The changes of pool of A As and their derivatives in the frontal cortex of the cerebral hemispheres at different duration of unilateral cerebral ischemia (UCI) (1 hour, 3 hours, 1 day) were studied in 18 rats. The analyses of the levels of AAs and their derivatives were carried out in the supernatant of protein-free tissue homogenates by reversed-phase liquid chromatography using chromatograph Agilent 1100. Results: Shifts of AAs content after 3 h of UCI observed included the raise of lysine, branched chain AAs (BCAA) – valine and leucine, depletion of the aromatic AAs (AAA) — tyrosine and tryptophan with the doubled ratio of BCAA/AAA. Moreover, we observed the decrease in the content of asparagine and essential/nonessential AAs and glycogenic/ketogenic AAs ratios. These changes were disappeared after 1 day of UCI. Conclusions: These results show possible mechanisms of development of the energy and neurotransmitter imbalances and their implications in the function of the brain with pathology studied. It is feasible that limitation on BCAA in this pathology will reduce consequences of mediator disturbancies caused by the deficiency of the precursors of biogenic amines – tyrosine and tryptophan.