Membrane hydrolysis o f carbohydrates in small intestine of growing, adult and old rats, obtained solution of lead salt of different doses together with food Текст научной статьи по специальности «Биологические науки»

Karimova Irodakhon Ibrohimjonovna, Physiology and biophysics department, Biology faculty, National University of Uzbekistan, Tashkent Sadikov Bahodir Asrorovich Bioorganic chemistry institute of Academy of Sciences of the Republic of Uzbekistan, Tashkent E-mail: [email protected]

MEMBRANE HYDROLYSIS O F CARBOHYDRATES IN SMALL INTESTINE OF GROWING, ADULT AND OLD RATS, OBTAINED SOLUTION OF LEAD SALT OF DIFFERENT DOSES TOGETHER WITH FOOD

Abstract: It was shown that the chronic intake of lead salt of different concentrations with food into the organism of growing, adult and old rats leads to different to negative alterations in the activity of carbohydrases of the small intestine mucosa. The higher concentration of lead salt, the more profound alterations in the hydrolytic function of the small intestine, and the mechanisms of membrane digestion of the growing organism turned out to be more vulnerable.

Keywords:

1. Introduction

Heavy metals are considered to be of particular ecological, biological and health protective importance among ecotoxicants of chemical nature. Mass pollution by salts of heavy metals of the environment leads to pronounced toxicoses ofplants, animals and humans. It was established that food contains various salts ofheavy metals and they have a serious influence on the health of the population [1, 2].

In our earlier research, it was shown that in offspring of rats, whose mothers were fed on a diet contaminated by heavy metals, the mechanisms of cavity and membrane hydrolysis of carbohydrates in the small intestine lag behind in development [3]. Chronic intake of lead salt at the dose of 5.0 mg/kg leads to a decrease in the hydrolytic function of the pancreas and small intestine of growing, adult and old rats [4].

2. Materials and methods

In our work we comparatively studied the age features that occur in enzymes of the lower stages of digestion and mitochondria of intestinal enterocytes as a result of intoxication of growing, adult and old rats with lead ions. The study of alterations in the digestive system

as a result of the ten-day poisoning by lead organisms of various ages in comparative terms has not been studied.

Lead chloride was administered orally by 1.0 mg and 5.0 mg per kg of body weight. Animals were observed within 10 days after intoxication. Lead chloride salt influenced differently on the change in the mass of the digestive organs and the body.

3. Results and discussion

In this experiment, the effect of different doses (1.0 mg/kg and 5.0 mg/kg) of lead chloride on the proximal-distal gradient of the small intestine of growing, adult and old rats was studied.

Initially, influence of a low dose (1.0 mg/kg) of lead chloride on the activity of lactase on the proximal-distal gradient of the small intestine of growing rats was investigated. According to this, lactase activity in the intestinal gradient decreased in the duodenal section in 37.5%, in the proximal one in 28.6%, in the medial one in 27.3% and in the distal one in 11.2%.

At the increase in the toxicant dose (5.0 mg/kg), activity of the enzyme has changed as follows. In the duodenal, proximal, medial and distal sections, activity of lactase decreased by 60.5, 3.1; 41.9 and 19.5%.

Figure 1. Change in lactase activity in the proximal-distal gradient of the intestine of growing rats

under the influence of the lead chloride salt (1. Experiment - 1.0 mg/kg and 2. Experiment - 5.0 mg/kg) (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1-duodenal, 2-proximal, 3-medial, 4-distal).

Hence, lead ion caused a decrease in intestinal lactase along the proximal-distal gradient in the body of growing rats. These alterations were reduced depending on the dose of the toxicant. At an increase in the dose of 5.0 mg/kg in the initial intestinal tract, repression is observed in the enzymes activity, while in the last distal section, on the contrary, the parameters were close to the control.

It can be seen that the activity of enzymes in the duodenal section of the intestine undergoes a stronger effect depending on the dose of the toxicant (Figure 1).

In experiments with adult rats under the influence of a low dose of lead chloride (1.0 mg/kg), lactase undergoes the following changes in different parts of the small intestine. According to the results, in the duodenal, proximal and medial sections of the small intestine, the activity of the enzyme decreases by 27.1 and 17.8, respectively. However, at moving to the distal section, the activity of the enzyme approaches the normal values. A significant decrease in lactase activity in the intestinal gradient occurs in the duodenal, proximal and medial sections. However, at going to the distal section, the opposite phenomenon is observed (Figure 2).

Figure 2. Change in lactase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of adult rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal).

At the influence of high dose of lead chloride (5.0 mg/kg) in adult rats, activity of lactase in the duodenal, proximal, medial and distal sections of the small intestine is reduced by 46.0, 44.5, 27.5 and 14.3%, respectively (Figure 2).

In the experiments with old rats, the following changes were observed. Under the influence of a low dose of lead chloride (1.0 mg/kg) in the duodenal, proximal, medial sections of the small intestine, respectively, decreases by 14.3, 9.4, 8.2, and the distal end index approached the control (Figure 3).

Figure 3. Change in lactase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of old rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal)

As a result of the high dose (5.0 mg/kg) of lead chloride in old rats, lactase activity in the duodenal, proximal, medial sections of the small intestine is

reduced by 28.6, 18.7, 12.7, respectively, and the indicator in the distal section approached the control (Figure 3).

Figure 4. Changes in saccharase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of growing rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal).

The next stage of the experiment was carried out with the determination of saccharase activity. Under the influence of a low dose of lead chloride (1.0 mg/kg) on growing rats in the duodenal, proximal, medial parts of the small intestine, the activity of saccharase decreased by 42.5, 51.8, 26.0, respectively, the distal indicator approached the control and was 6.1% (Figure 4).

As a result of a high dose of toxicant (5.0 mg / kg), the following changes in saccharase activity in growing

rats are observed. The activity of this enzyme in the duodenal, proximal, medial and distal sections of the small intestine decreased by 66.7, 67.9, 42.0 and 18.2%, respectively (Figure 4).

In experiments with adult rats, a decrease in saccha-rase activity in the duodenal, proximal and medial sections was observed, respectively, at 43.2, 38.9 and 36.1%, as the approach to the distal section increases in enzyme activity was observed (Figure 5).

Figure 5. Change in saccharase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of adult rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal)

At the administration of a high dose (5.0 mg/kg) of lead chloride to adult rats, it was recorded a decrease in the activity of saccharase in the duodenal, proximal, me-

dial and distal sections of the small intestine, respectively, by 61.4, 58.3, 42.7 and 8.4% (Figure 5).

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Figure 6. Change in saccharase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of old rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal)

In experiments with old rats, enzyme activity of the through the proximal-distal gradient undergoes peculiar changes. In experiments with a low dose (1.0 mg/kg) of lead chloride, saccharase activity in the duodenal and proximal sections decreased by 20.9 and 20.5%, respectively, in the medial and distal sections approached the control parameters (Figure 6).

As a result of the high dose of lead (5.0 mg/kg) in saccharase activity in growing rats, the following changes are observed. Enzyme activity in the duode-

nal, proximal, medial and distal sections of the small intestine decreased by 37.5, 27.3, 15.0 and 7.2%, respectively (Figure 4).

The next stage of the experiment was carried out with the determination of maltase activity. Under the influence of a low dose of lead chloride (1.0 mg/kg) on growing rats in the duodenal, proximal, medial parts of the small intestine, in maltase activity repression was observed, at 31.2, 38.1, 30.8%, respectively, approaching the distal section was 16.7% (Figure 7).

Figure 7. Changes in maltase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of growing rats (n = 8)

Note: * - P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal)

As a result of a high dose of toxicant (5.0 mg/kg) in denal, proximal, medial and distal sections of the small maltase activity in growing rats, the following changes intestine decreased by 45.7, 50.9, 48.2 and 26.7%, respec-are observed. The activity of this enzyme in the duo- tively (Figure 7).

Figure 8. Change in maltase activity under the influence of lead chloride (1 experiment - 1.0 mg/kg and 2 experiments - 5.0 mg/kg) in the proximal-distal gradient of adult rats (n = 8)

Note: * P < 0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1-duodenal, 2-proximal, 3-medial, 4-distal)

In experiments with adult rats, it was observed a decrease in the duodenal, proximal and medial parts of the lower doses (1.0 mg/kg) of lead chloride, respectively, by 41.3, 42.9 and 32.8%; in the distal section, an approach to the control reading was observed (Figure 8).

As a result of the high dose of lead (5.0 mg/kg), the maltase activity in adult rats in the duodenal, proximal,

medial and distal sections ofthe small intestine decreased by 59.0, 56.6, 45.3 and 13.9%, respectively (Figure 9).

In experiments with old rats under the influence of a low dose (1.0 mg / kg) of lead chloride in maltase activity in the duodenal and proximal sections, respectively, 25.3%, in the medial section by 28.8%, in the distal section there is no change (Figure 9).

Figure 9. Change in maltase activity under the influence of lead chloride (1 experiment - 1.0 mg / kg and 2 experiments - 5.0 mg / kg) in the proximal-distal gradient of old rats (n = 8)

Note: * - P <0.05; ** - P < 0.01; *** - P < 0.001 - confidence level relative to the control; On the X-axis, the small intestine (1 - duodenal, 2 - proximal, 3 - medial, 4 - distal)

As a result of the high dose oflead (5.0 mg / kg), maltase activity in old rats in the duodenal, proximal and medial divisions ofthe small intestine decreased by 45.6, 48.1, 41.6%, respectively, in the distal section, enzyme activity rises and approaches the control readings (Figure 9).

3. Conclusion

Based on obtained results, it can be concluded that a low (1.0 mg/kg) and high (5.0 mg/kg) dose of lead chloride in adults and old rats resulted in a change in carbohydrase activity from the proximal-distal gradient of the small intestine. The topography of the distribution of lactase and maltase throughout the intestine lumen in animals of all ages has not changed, but saccharase distribution undergoes a change. The decrease in the activity of common enzymes in each part of the intestine is recorded in all age representatives. In growing rats, these changes became more apparent compared to other age groups.

Poor development of digestive enzymes and high absorption capacity of the small intestine wall of growing organisms in comparison with representatives of other age groups can be the reasons for such changes. Therefore, sometimes pure proteins that are not split

into amino acids can freely pass into the blood. As a result of this property of the small intestine of growing rats, they are more likely to have food poisoning compared to other groups. Hence, under the influence of toxicants, growing rats are more strongly influenced compared to adults and old rats. In addition, carbohy-drases activity in the small intestine is not the same and the rate of absorption of monosaccharides varies. For example, in the proximal part of the small intestine, glucose is absorbed three times faster than in the distal part. The composition of food, the general condition of the body, environmental factors affect the rate of absorption of carbohydrates. According to studies, 3% of the lead coming from food is absorbed into the small intestine. In hungry animals, this indicator is doubled. The absorption of metal along the gradient of the small intestine is not the same and in the medial section is higher in percentage. The influence of calcium with such absorption in the body is revealed. Lead with food inhibits the work of food enzymes in the small intestine and as a result digestion decreases. This condition negatively affects intestinal peristalsis.

Thus, the results of the experiments show that the intake of heavy metal - lead chloride from the food, significantly reduces the hydrolytic function of the small intestine with respect to various sugars. The degree of severity of the shifts depended, first, on the age of the animals and, secondly, on the enzymatic activity being determined. Comparison of the results obtained on animals of different ages indicates that the more vulnerable to intoxicant were the growing organisms and less-old ones.

From the results of the experiments, it can be concluded that the chronic intake of lead salt from the food has a negative effect on the mechanism of assimilation of nutrients. In our experiments, the use of a high dose gave deeper shifts than a low dose, in addition, lead salt intoxication caused significant disturbances in the function of the small intestine in a growing organism. These indicate that a growing body is more vulnerable to the

effects of an unfavorable factor than an adult or an old organism.

Our data confirms once again the fact that the daily intake of heavy metal salts with the food acts as chronic stress, causing a change in the hormonal status, changing the function of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid systems, leads to certain shifts in the mechanisms of cavity and membrane digestion [5, 6, 7]. These data are consistent with the results of other studies in which it was shown that chronic effects are unfavorable environmental factors leads to deep changes in the structure and function ofthe digestive system ofa growing organism [8, 9, 10, 11, 12]. In old organism, the reaction to the effect is weakly expressed, obviously connected with the fact that in the old age the metabolism decreases, the hydrolytic function ofthe digestive organs slows down the passage of food along the gastrointestinal tract [13].

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