α-2-macroglobulin (α-2-MG) is one of the main regulators of intercellular relationships and is synthesized by virtually all cells (hepatocytes, hematopoietic cells, fibroblasts, myocytes, epithelial and nerve cells). It is shown that macroglobulin is capable of forming complexes with almost all currently known proteases regardless of their origin. α-2-MG is one of the main factors that contributes to the binding of foreign antigens by the immune system cells and forms complexes with nearly all currently known proteases, independent of their origin. The role of α-2-MG in the development of pathological processes continues to be actively explored today. α-2-MG activity was determined in tissue samples (serum, cerebral cortex, hypothalamus, heart, lungs, liver and kidneys) of intact rats (7-8 months and 17-18 months) and in rats on the background of pathological states development (depression, alcoholism and hypotension) by a highly sensitive enzymatic method. Depression was simulated by the stress of “not-avoiding” in an isolated chamber, which contributed to the development of the pathological symptom complex in animals ("learned helplessness"); hypotension was achieved by injections of 2.5% of chlorpromazine; "two bottle choice method" was used for alcoholisation during 10 months. Control I - 7-8 months rats; control II - 17-18 months rats. Blood pressure (BP) was recorded by tonometer, the cuff was put on a tail. Depression was accompanied by hypertension with higher blood pressure (221.6 ± 9.8 mmHg, in the control I - 100.8 ± 6.6 mmHg) than alcoholism (176,7 ± 20 68 mm Hg, in the control II - 130,00 ± 12,25 mmHg); blood pressure increases with age; at hypotension BP was reduced by 35 ± 5 mmHg. At depression the α-2-MG activity significantly (by one order of magnitude) increased in all tissues except the brain cortex (unchanged); in young animals control was much lower than that of old ones (all tissues). Alcoholisation reduced the α-2-MG activity dramatically, particularly in the hypothalamus, the lungs, heart and kidneys (by two orders of magnitude) in the other samples - 6-10 times. The α-2-MG activity in hypotensive rats was reduced in 10 times in all tissues except the blood serum (increased). The activity of α-2-MG increases with age and its dramatic increase at depression is also in agreement with the ideas that the depressive like states are evolved precisely on the background of the immune system activation. Alcohol has negative impacts at all the links of immunity. Since macroglobulins play a significant role in the humoral and cellular immune responses, the observed changes in the activity of α-2-MG may indicate both the activation and the suppression of the immune system in the development of pathology. Excess α-2-MG created by complexation with proteases, promotes apoptosis of damaged cells, promotes phagocytosis activity regulation by the cytokines and is aimed at localization of necrosis focus. Thus, fluctuations in the α-2-MG activity faithfully reflect age-dependent and pathologic changes in the state of immunity.
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