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Activities of digestive enzymes (maltase, alkaline phosphatase, amino peptidase M, and glycyl-L-leucine dipeptidase) in small and large intestine, liver, and kidney were studied in rats of different ages kept in normal (8) and low (3) amounts of pups per litter. The low-protein diet for 10 days at once after weaning was found to change the mass of the organs and their digestive enzyme activities in all studied rat groups. The revealed changes were more prominent in rats kept under conditions of breast-overfeeding. In adult animals of this group, distribution of the alkaline phosphatase activity along the small intestine differed from that in control rats. The obtained results seem to confirm the fact that any disturbance of the nutrition quality in early ontogenesis leads to disturbance of the "metabolic programming of enzyme systems" of digestive and non-digestive organs.

Restriction of protein in nutrition of rat pups weaned at different terms has been found to produce changes in activities of digestive enzymes (maltase, alkaline phosphatase, aminopeptidase M, and glycyl-L-leucine dipeptidase) in the small and large intestine both at once after cessation of nutrition with low-protein diet for 10 days and 4 months later. In adult animals after the earlier or later weaning there are observed not only a decrease or increase of the enzyme activities, but also a different type of distribution of the alkaline phosphatase activity along the small intestine, which is more pronounced in the lately weaned rats. Thus, disturbance of metabolic programming of enzyme systems of the small and large intestine due to a change of quality of nutrition in early ontogenesis depends on terms of weaning of animals.

Low protein content in the ration of rat pups during transfer from mixed to definitive nutrition (days 21-30 of life) has a negative impact on digestive function of the small intestine and trophic and barrier functions of the large intestine, liver, and kidneys and increases (sucrase, glycyl-L-leucin dipeptidase) or decreases (alkaline phosphatase, aminopeptidase M, glycyl-L-leucine dipeptidase) enzyme activities in these organs in 6-month-old rats. Protein deficiency during the early ontogeny modulates functioning of the enzyme systems in digestive and non-digestive organs in adult life, which can lead to the development of not only gastrointestinal, but other visceral diseases.

It is shown, that the value of Km for maltase, alkaline phosphatase, aminopeptidase M and glycyl-L-leucinedipeptidase, prepared from the jejunum and ileum of 10-day rat litter in membrane and soluble forms in most cases differed but a little in control animals and the rat litter whose mothers in the period of lactation had a diet with 2.5-fold reduced content of protein, and did not change under action of injected thyroxin and dexamethasone. It may be assumed that in the given experimental conditions each of the investigated digestive hydrolases in membrane and soluble forms represents the same enzyme. In conditions of the protein insufficiency in lactating females diet and under action of exogene hormones, apparently, no significant changes occur in structure of synthesised enzymes.

It has been found for the first time that protein deficit in female's nutrition during prenatal development of the offspring is accompanied by considerable changes in the activity of intestinal digestive enzymes and of the same hydrolases in the colon, liver and kidneys both in early and in late ontogenesis. It seems possible that changes of the small intestine enzyme functions and hydrolytic functions of other digestive and non-digestive organs in result of an unfavorable early "metabolic/nutritional programming" may be crucial in disorders of metabolic processes leading to development of diseases of risk in adult life.

Protein deficiency in female rats diet during pregnancy and lactation resulted in deceleration of induction of sucrase both forms in the jejunum and ileum; in acceleration of induction of the maltase membrane from in the jejunum; and in suppression of the lactase membrane form in the ileum; in earlier forming of the adult-type distribution of activity of the membrane form of intestinal alkaline phosphatase and in a decrease in activity of the enzyme soluble form. The findings are corroborated by a suppression of activities of the membrane and soluble forms of the small intestine digestive enzymes in 30-day old rat pups fed with a control (adequate) ration starting 21 days after the birth.

The effects of sodium nitrate on the activity of digestive enzymes in mucosal and submucosal layers of the small intestine as well as in liver and kidney were studied in the growing rats maintained on either standard or protein-free diets. The enzyme systems were more sensitive in the growing rats to protein deprivation than in adult animals. However, the digestive enzymes were more resistant against nitrate intoxication in the growing rats.