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Mamadaliyeva Nodira Isakovna, Post-doctoral student Laboratory of Metabolomics, Acad. O. A. Sadykov Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences E-mail: [email protected] Saatov Talat Saatovich, Professor, Head of laboratory Laboratory of Metabolomics, Acad. O. A. Sadykov Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences E-mail: [email protected] Umerov Oybek Ilyasovich Junior researcher Laboratory of Metabolomics, Acad. O. A. Sadykov Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences E-mail: [email protected]
INFLUENCE OF HYPOBARIC HYPOXIA ON THE CEREBROSIDES AND SULFATIDES COMPOSITION OF RAT CARDIAC TISSUE
Abstract: The purpose of the study was to analyze the qualitative and quantitative composition changes of cerebrosides in the cardiac tissue in the process of its adaptation to chronic hypobaric hypoxia. The experiments were carried out on white rats, males, hypobaric hypoxia was reproduced by "lifting to a certain height" in a special chamber. Increase in the number of total cerebrosides and the absolute content of sulfatides was observed during adaptation to chronic hypoxia of various intensities.
Keywords: hypobaric hypoxia, cerebrosides, sulfatides, cardiac tissues.
Today, the main cause of morbidity, disability, and mortal- ids, glycerolipids and sterols are the main component of these ity in the world are cardiovascular diseases. They are the prime membranes, but their chemical structure, physical properties cause of death among industrialized countries population, be- and specialized enzymatic mechanism differ from other lipids. ing cause of approximately 30 to 50% deaths [8]. They are one of the most diverse types of lipids in chemical
Diseases progression severity, as well as their outcome structure and biological function. This category includes hun-is ultimately determined by the characteristics of secondary dreds of compounds with the sphingoid base as a common nonspecific metabolic diseases, as well as the degree of desta- fragment. The recent interest in studies of the selected sphin-bilization of cell membranes suffering from hypoxic condi- golipids categories role, which are sulfatides and cerebrosides, tions. A wide variety of human diseases cause hypoxia which is attributed to a number of properties of these lipids. Due to is considered the most universal pathological condition. Hy- this interest, our understanding of the functions and metabo-poxia determines severity ofischemic heart disease due to the lism of cerebrosides has significantly increased over the past fact, that it is the main pathophysiological feature of various few years. Their participation in the regulation of the physical cardiovascular diseases [10]. properties of cell membranes, the activity of membrane en-
Recent studies of the pattern and progression of patho- zymes and signal proteins has already been proven. However, logical processes related to cardiovascular hypoxia, indicate little is known about in various pathologies that cause disorder that changes in the structure and function of cell membranes in their homeostasis [5, 9, 12].
is an important link in understanding the manifestation of The purpose of this study is to investigate the effect of
this pathology [4, 7]. In many cases, the cause of these con- hypobaric hypoxia on the content of the total amount and ditions is the violation of the integrity of the lipid phase of percentage of cerebrosides and sulfatides in the heart tissues the bilayer membrane, which shows the importance of lipids of experimental animals.
in the pathogenesis of hypoxic states [11]. Cell membranes Materials and techniques. The experiments were carried
have an extremely complex composition and structure, due to out on outbred adult male rats weighing 250-280 g. Hypo-participation in a wide range of cellular processes. Sphingolip- baric hypoxia was caused in animals of the experimental group
Section 1. Biology
by the daily 4-hour exposure in hyperbaric chamber [1] for 10 days. The pressure in the chamber was 462 mm Hg for the first group ("height" of4000 m above sea level), 405 mm Hg for the second ("height" of 5000 m above sea level), 354 mm Hg for the third ("height" of 6000 m above sea level), and 308 mm Hg for the fourth ("height" of 7000 m above sea level). The control group of animals was kept under normal conditions in animal quarters. Animals were killed by the method of decapitation. The extracted hearts were weighed and homogenized in liquid nitrogen.
Extraction of total lipids and their purification from nonlipid impurities was carried out according to the Folch extraction procedure [6] modified by Kates [2], using chloroformmethanol mixture (2:1). Extraction was carried out in 60 minutes, at room temperature, during the extraction; the contents of the flasks were occasional shaking. The technique allows sufficiently complete (98-100%) extraction of tissue lipids. Total lipid extract (TLE) was stored at 0-4 °C and used to measure the amount of lipids and their fractionation. The amount of total cerebrosides and their individual fractionations was determined
by the galactose content, which was determined according to the method proposed by Radin and associates, in combination with the method of Svennerholm [3].
Results and discussion. The literature shows that prolonged exposure to hypoxic conditions causes the occurrence of adaptive changes at various levels of cellular structure in both humans and animals to allow maintenance of the required homeostasis level under oxygen starvation [11].
Our research has shown that hypobaric hypoxia led to an increase in the number of total cerebrosides (Figure 1.) and changes in the content of individual fractions (Table 1.).
Table 1 shows a clear trend of increase in the total number of cerebrosides in the heart of animals subjected to hypoxia, although these changes were not always statistically significant (P>0.05). The first group and the second group had a slight increase in the total content of glycolipids in the heart by 1.1% and by 1.5% respectively. The total cerebrosides content was significantly different from the control in only 3 and 4 groups (10.61 and 10.68 mmol/kg of raw tissue versus 90.90 mmol/kg in the control group).
Table 1. - Total cerebrosides content changes in the tissues of the heart during hypobaric hypoxia (galactose mmol/kg of tissue, n=12)
Total cerebrosides content
Absolute values % vs control T T T1 T3
Control group (n =12) 9.90 ± 0.27
Group I (гипоксия 4000 м, n=12) 10.01 ± 0.25 101.11 0.30
Group I (гипоксия 5000 м, n=12) 10.05 ± 0.25 101.52 0.41 0.11
Group I (гипоксия 6000 м, n=12) 10.61 ± 0.22 107.17 2.04 1.80 1.68
Group I (гипоксия 7000 м, n=12) 10.68 ± 0.18 107.88 2.40 2.17 2.05 0.25
Table 2. - Changes in the cerebrosides content in the tissues of the heart after 10 exposures to hyperboric hypoxia for 4 hours (cerebroside mmol/kg of raw tissue, n=12)
Sulfatides Cerebrosides
Cerebroside mmol /kg of raw tissue % Cerebroside mmol /kg of raw tissue %
Standard 2.66±0.08 26.86 7.24±0.19 73.14
4000 m 2.94±0.08 29.39 7.07±0.17 70.61
5000 m 3.03±0.09 30.16 7.02±0.14 69.84
6000 m 3.52±0.10 33.19 7.09±0.13 66.81
7000 m 3.60±0.06 33.70 7.08±0.12 66.30
In order to study this process deeply, we created fractional separation of cerebrosides and sulfatides in our experiments by the means of thin-layer chromatography. Data in table 2 shows the similarity in nature of the changes observed in the glycolipid fractions. An increase in the relative content of the sulfatide fraction can be seen in all groups; the sulfatide fraction increased by 10 and 13% respectively in groups with moderate hypoxia (4000 and 5000 m), whereas, the increase
in sulfatide was 32 and 35% in groups with intensive hypoxia (6000 and 7000 m). A decrease of cerebroside content (both percentage and absolute) was detected in the fraction of cerebroside, regardless of the intensity of hypoxia.
The literature shows that the quantitative ratio of cere-brosides and sulfatides depends on the activity of enzymes of the glycosidase group, in particular, galactocerebroside-3-O-sulfatase, which catalyzes the abstraction of the sulfatide group
from galactose residues in sulfatides, and thereby maintains the balance between these compounds. The detected increase of sulfatides in these pathologies indicates that the activity of this enzyme is suppressed in these cases, which ultimately leads to the accumulation of sulfatides in the cell membranes [8].
Therefore, the results of the conducted study allow us to conclude that the cerebroside composition of the cardiac tissue undergoes a change, which is in direct correlation with the intensity of hypobaric hypoxia.
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