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Activity of cathepsins B and C was increased 1.8-2-fold in spleen simultaneously with a decrease 3.8-fold in the rate of protein renewal in the tissue lysosomal fraction within 4 days after antigen stimulation of rats, maintained within 45 days on a diet containing 5% of protein. Activation of these thiol-dependent proteinases appears to occur in response to development of immunodepressive conditions and may be related to alterations in the rate of their biosynthesis.

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Activity of cathepsins A, B, C and D and protein half-life T1/2 in rat liver, spleen and thymus tissues, content of antibody-producing cells in spleen, titer of antibodies and the complement activity were studied after antigen stimulation accompanied by vitamin B6 deficiency. Deficiency of vitamin B6 caused a distinct decrease in immune response and in activation of thiol-dependent proteinases in thymus, while the enzymatic activity was lowered in liver tissue. At the same time, the protein T1/2 was increased by 39% in liver tissue and decreased by 36% in thymus. These data suggest the importance of lysosomal thiol-dependent proteinases in immunogenesis.

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Total activity of cathepsins A, B, C, D as well as of arylsulfatases A and B were studied in liver, spleen, thymus tissues of rats after peroral administration of vitamin A at a daily dose of 30,000 IU within 3 days and the following immunization with sheep erythrocytes. Under conditions of immunization with T-dependent antigen the immunostimulating effect of vitamin A was accompanied by the distinct activation of lysosomal proteinases in liver and spleen tissues but did not affect the functional state of thymocyte lysosomal apparatus. The reaction of lysosomal hydrolases observed was considered as one of biochemical steps in development of humoral immunity.

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In experiments on rats it was shown that the rations containing casein (18 and 5% calorific value) and fatty component completely substituted for butter (30 and 50% calorific value), in the presence of hypersholesterolemia, hyper-beta-lipoproteinemia and hypo-alpha-lipoproteinemia, induced changes in the elasticity of the aorta, coronary and intrarenal arteries. Swelling, separation, disappearance of elasticity and tinctorial properties of elastic fibers of tunica media vasorum and internal elastic membrane were observed in the animals given the above rations during 1-6 months. In the coronary and intrarenal arteries these changes were attended by vacuolization and destruction of the medial smooth muscle cells. The vascular alterations were most early and drastically manifest in the animals that received the ration with 5% protein and 50% butter. No vascular changes were noted in the animals given sunflower oil in similar amounts and during the same period as butter, with 18% protein in the ration. Such action of sunflower oil was not pronounced when the ration contained 5% protein, large amount of cholesterol (1% of the ration mass) or trans-isomers of unsaturated fatty acids.

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The activity of cathepsins A, B, C, D, phospholipases A1 and A2, and aryl sulphatases A and B was studied in hepatic lysosomas, adipocytes of epididymal fatty tissue and in platelets of rats aged 2,5 and 24 months differing in the character of milk feeding. It was found that excessive feeding in the neonatal period resulted in a decrease of the lysosomal proteinase activity by 18-33% in 24-month animals, while phospholipase A2 activity rose 1,4-2.2-fold. Phospholipase A2 activity proved to be also increased in adipocytes of obese rats. Obese rats' platelets were characterized by a drastic (2-3.5-fold) activation of cathepsin C, and phospholipase A1 activity rose by 55% at all the stages of the ontogenesis. It is suggested that the changes in the lysosomal hydrolases activity may reflect the platelet function in the disordered lipoprotein metabolism.

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It has been shown in experiments on rats fed a low-protein diet (5% according to the caloric value) that sunflower oil introduced into the diet in a high amount (50% according to the caloric value) does not exert any protective effect on the wall of the blood vessels (aorta, coronary and intrarenal arteries). The animals develop moderately marked morphological alterations similar to those seen in feeding a low-protein diet with high butter content. These alterations can be described as follows: the elastic fibers of the intima and media lose the tinctorial properties and elasticity; they swell and branch in some places; the destruction sites demonstrate the clusters of neutral and acid mucopolysaccharides.

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It has been demonstrated in experiments on rats that prolonged (for 1-6 months) use of the diet with protein deficiency or excess (5 and 30% respectively as regards caloricity) determines the development of injuries to the aortal wall and arteries of the heart and kidneys. Vascular elasticity shows abnormality, which is the most pronounced if the animals are given the low-protein diet including butter. Sunflower oil has a protective effect which becomes manifest provided that the animals receive the high-protein diet.

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The authors studied the effect of prolonged (7 months) keeping of the animals on the diet with an excess amount of fat (50% of butter) on some characteristics of lipid metabolism and activity of phospholipases A1 and A2, as well as on the activity of a number of lysosomal hydrolases in adipocytes, the liver, kidneys and spleen of rats. Selective activation of lysosomal phospholipases A was demonstrated, being the most marked in adipocytes and the liver. It is assumed that the growth of phospholipase activity is a specific adaptive response of the body, aimed at the enhancement of degradation of lipids, particularly phospholipids, under the conditions of excess fat supply with food. Alternatively, it may be suggested that the enhancement of intralysosomal degradation of cell membrane structures is a consequence of their fat degeneration.

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Animals who received butter in an amount constituting 30 and 50% of the diet caloric value showed changes in the aortal walls and in intraorgan arteries of the heart and kidneys. These changes were largely marked by dystrophic impairment of vascular elasticity. They were more pronounced and occurred more frequently in rats who had received elevated amounts of butter. In these animals, changes in elastic fibers were aggravated by dystrophy of smooth muscle cells of the media whose cytoplasm demonstrated vacolization. No vascular changes were detected in animals who had been given sun flower or olive oil in an amount constituting 30 and 50% of the diet caloric value.

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Experiments involving chronic introduction of ethanol (36 per cent of caloric value) as a part of a specially devised liquid ration demonstrated the trainability of rats to sharply decrease, their antistress resistance to significantly decline, especially in rats kept on a low-protein diet. A general tendency toward a reduced activity of acetylcholinesterase in different sectors of the brain was revealed both in animals receiving alcohol against the background of a normal protein allowance and in those kept on a low-protein diet (when compared with the enzyme activity in animals maintained on a ration with a normal of protein).

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