The Physiological Model of Na⁺-Dependent Transporters for Glucose and Amino Acids in Rat and Turtle

Conditions in rat and turtle small intestine tissue where glucose and glycine transport is inhibited while glucose-induced Na+ transport is preserved are described. The generally accepted model for the Na+-dependent transporter (а single channel for the Na+ and nutrient) does not account for the data obtained from the analysis of the interaction between the transport of glucose, glycine, and Na+ at different temperatures and the effect of inhibitors оn these рroсеssеs. The phenomenon of temperature uncoupling of Na+ and nutrient transport саn best bе described bу а two-pathway model with а gate mechanism. According to this model, the Na+-dependent transporter has at least two pathways: оnе for Na+ and another for nutrients. The model рrovidеs for the passage of Na+ in both directions along а channel opened bу glucose. Experiments are carried out using the addition of glucose and glycine on backgrounds of glycine and glucose, respectively. It has been hypothesized that when all three transporters (for Na+, glucose and glycine) are unite in a single structure, then there should be “competitive relations” between short-circuit current changes on glycine and glucose for sodium ions passing through its transporter.

Rat small intestine absorption and membrane digestion in the process of aging

Recently, in our experiments, we used the short-circuit current technique to study the kinetic constants for nutrient transporters in rat gastric-intestinal tract and the thickness of the intestinal unstirred layer near the mucosa surface. It was shown that, during the process of aging, the number of nutrient monomer transporters in the small intestine increases twofold, whereas the affinity of transporters to the correspondent nutrients remains unchanged. The situation for peptides may be opposite. The layer thickness in the vicinity of the mucosa surface, measured through glucose, decreased during the process of aging. It was suggested that, in old rats, the role of the digestive volume is more important, which results in an increase of the number of nutrient monomer transporters.

Atherosclerosis originating from childhood:Specific features

Atherosclerosis is extremely widespread.Traditionally,it is considered a disease of older people,who most often experience problems with the heart and blood vessels.While much attention from the scientific community has been paid to studying the association between aging and atherosclerosis,as well as its consequences,there is evidence that atherosclerosis occurs at an early age.Atherosclerosis may form both during intrauterine development and in childhood.Nutrition plays an important role in childhood atherosclerosis,along with previous infectious diseases and excess weight of both the child and the mother.In the present review,we examined the development of atherosclerosis and the prerequisites in childhood.

Mitochondrial dysfunction and mitochondrial DNA mutations in atherosclerotic complications in diabetes

Mitochondrial DNA(mtDNA) is particularly prone to oxidation due to the lack of histones and a deficient mismatch repair system.This explains an increased mutation rate of mtDNA that results in heteroplasmy,e.g.,the coexistence of the mutant and wild-type mtDNA molecules within the same mitochondrion.In diabetes mellitus,glycotoxicity,advanced oxidative stress,collagen cross-linking,and accumulation of lipid peroxides in foam macrophage cells and arterial wall cells may significantly decrease the mutation threshold required for mitochondrial dysfunction,which in turn further contributes to the oxidative damage of the diabetic vascular wall,endothelial dysfunc-tion,and atherosclerosis.

Association of the level of heteroplasmy of the 15059G>A mutation in the MT-CYB mitochondrial gene with essential hypertension

AIM: To examine whether the heteroplasmy level for 15059G>A mutation in the mitochondrial genome might be associated with essential hypertension. METHODS: This cross-sectional study involved 196 unrelated participants randomly selected from general population (90 males and 106 females) who underwent a regular medical check-up at the Institute for Ath-erosclerosis Research (Moscow, Russia). One hundred and twenty of them (61%) had essential hypertension, and 76 (39%) were apparently healthy normotensive persons. The level of heteroplasmy for 15059G>A mutation occurring in the coding region of cytochrome b gene (MT-CYB) of mtDNA isolated from the blood leukocytes, was quantified using DNA pyrosequencing method. RESULTS: The 15059G>A heteroplasmy level ranged between 4% and 83%, with a median level of 31%. Between the upper and lower quartiles of 15059G>A heteroplasmy distribution, significant differences were observed for patients' age, systolic blood pressure, and triglyceride levels. 15059G>A heteroplasmy correlated both with age (r = 0.331, P < 0.001) and the presence of hypertension (r = 0.228, P = 0.002). Regression analysis revealed that the age explains 12% variability of 15059G>A heteroplasmy, and hypertension independently explains more 5% variability. The 15059G>A heteroplasmy exceeding 31% was found to be significantly associated with a higher risk of essential hypertension (odds ratio 2.76; P (Fisher) 0.019]. The study participants with high 15059G>A heteroplasmy level were found to have significantly higher age (P < 0.001) and the prevalence of essential hypertension (P = 0.033), as compared to those with low 15059G>A heteroplasmy level. These observations suggested a positive correlation between the level of 15059G>A heteroplasmy and essential hypertension. CONCLUSION: This study provides the evidence of association of mtDNA 15059G>A mutation heteroplasmy with essential hypertension.

Intimal pericytes as the second line of immune defence in atherosclerosis

Inflammation plays an essential role in the development of atherosclerosis. The initiation and growth of atherosclerotic plaques is accompanied by recruitment of inflammatory and precursor cells from the bloodstream and their differentiation towards pro-inflammatory phenotypes. This process is orchestrated by the production of a number of pro-inflammatory cytokines and chemokines. Human arterial intima consists of structurally distinct leaflets, with a proteoglycan-rich layer lying immediately below the endothelial lining. Recent studies reveal the important role of stellate pericyte-like cells(intimal pericytes) populating the proteoglycan-rich layer in the development of atherosclerosis. During the pathologic process, intimal pericytes may participate in the recruitment of inflammatory cells by producing signalling molecules and play a role in the antigen presentation. Intimal pericytes are also involved in lipid accumulation and the formation of foam cells. This review focuses on the role of pericytelike cells in the development of atherosclerotic lesions.

Neonatal Exposure to the Dipeptidyl Peptidase-IV Inhibitors Diprotin A and Sitagliptin Induces Depression-Like Behavior, Anxiety, and Latent Aggression in Adolescent and Adult Rats

Emotional and motivational disorders in adults are often considered to be the result of altered neurodevelopment. Clinical and experimental data provide evidence that serine protease dipeptidyl peptidase-IV (DPP-IV, EC 3.4.14.5) is involved in the pathophysiology of psycho-emotional disorders. Recently, we have shown that adolescent and adult rats exhibit an increase in anxiety and depression-related behaviors after neonatal administration of a synthetic non-competitive inhibitor of DPP-IV, methionyl-2(S)-cyano-pyrrolidine. In the present study, we tested the effects of two competitive, selective DPP-IV inhibitors, sitagliptin (4 mg/kg) and diprotin A (2 mg/kg), administered at postnatal days 5 - 18 on the emotional and motivational behavior of adolescent and adult rats. We observed increased anxiety in one-month-old diprotin A- or sitagliptin-treated rats in the elevated plus maze;diprotin A also enhanced the animals’ anxiety score using a ranked scale for evaluating anxiety and phobias. In the sucrose consumption and preference test, depressive-like behavior was pronounced in both the diprotin A- and sitagliptin-treated one-month-old animals, while only the diprotin A-treated rats exhibited a decrease in sucrose consumption at the age of 2 months. The diprotin A-treated rats also demonstrated behavioral despair and decreased activity in the forced swimming test within 1 - 3 months of age. Increased aggression was observed in 1 - 3-month-old diprotin A-treated rats and in two-month-old sitagliptin-treated rats. These findings support the hypothesis that DPP-IV is involved in the genesis of emotional and motivational disorders. Additionally, the results show that diprotin А impairs the adolescent and adult rats’ behavior more significantly than sitagliptin when the animals were treated with the DPP-IV inhibitors in the early postnatal period.

Hypoxic Preconditioning Eliminates Differences in the Innate Resistance of Rats to Severe Hypoxia

Hypoxic preconditioning is able to increase the body’s resistance to hypoxic/ischemic stress. Understanding how to apply the hypoxic response to initiate the protective mechanism of ischemic preconditioning is a high priority. However, the relationship between innate resistance to hypoxic stress and preconditioning efficiency of moderate hypoxia has been poorly studied. In our work, the efficiency of single moderate hypobaric hypoxia (HBH) for resistance to severe hypobaric hypoxia (SHBH) was studied on intact rats and those pre-tested under SHBH with low, intermediate and high resistance to hypoxia. HBH has a significant preconditioning action on the resistance to hypoxia over a wide range from 270 to 1464 s (4.5 to 24.5 min) and at the same time eliminates the differences in the endurance under SHBH between all rat groups. It is concluded that 1) HBH preconditioning efficiency does not depend on an innate resistance to SHBH and prior hypoxic experience of rats;and 2) the pretesting to severe hypoxia has no value for predicting the hypoxic preconditioning efficiency and study of adaptive mechanisms.

The Acoustic Sensorimotor Gating Predicts the Efficiency of Hypoxic Preconditioning. Participation of the Cholinergic System in This Phenomenon

Moderate one-off hypobaric hypoxia (HBH) provokes preconditioning and prolongs the resistance (T, the time before apnoea) to severe hypobaric hypoxia (SHBH). Hypoxic preconditioning has therapeutic potential;however, the efficiency of hypoxic preconditioning varies greatly and the methods for its preliminary evaluation are absent in both animals and humans. This rodent study evaluates the dependence of SHBH resistance, initiated by HBH, on the rate of sensorimotor gating estimated in the model of the acoustic startle prepulse inhibition (PPI). A stable negative correlation was found between PPI and T. Low doses of the α7 nicotinic receptor agonist, PNU-282987 (PNU), and more pronouncedly dimethyl sulfoxide (DMSO) (a PNU solvent), inverted the correlation between PPI and T from negative to positive. The DMSO and PNU effects were reversed at PPIs of 0.36 - 0.40 (36% - 40%). DMSO increased T values by 52.2% ± 9.7% in the region of lower HBH efficiency (PPI ≥ 0.40) and reduced it by 35.2% ± 9.3% in the region of higher HBH efficiency (PPI < 0.40). PNU reduced both DMSO effects. The involvement of the central cholinergic mechanisms was substantiated in both DMSO and PNU influences on HBH. In conclusion, 1) PPI can be used to predict the efficiency of hypoxic preconditioning and to study its mechanisms, 2) two opposite cholinergic PPI-related mechanisms participate in the preconditioning effects of HBH, 3) the sensitivity of rats to DMSO and PNU diverges when the PPI is 0.36 - 0.40, and 4) DMSO can enhance resistance to severe hypoxia in the region of the lower preconditioning efficiency of HBH at PPI ≥ 0.4.

Impact of Connexins on Atherogenesis: A Brief Review

Connexins family in humans consists of 21 highly conserved proteins that are responsible for contact formation between cells. On the cell surface, connexins form hemichannels, or connexons. Two hemichannels brought together form a gap junction, a form of intercellular contact that allows for direct transfer of material and signals between the adjacent cells. Gap junctions serve for transporting ions and other soluble, low molecular weight molecules therefore synchronizing the microenvironment of the contacting cells and maintaining cell and tissue homeostasis. Impairment of gap junctions is associated with different pathological conditions. Importantly, it has been described in atherosclerosis, which causes local cellular dysfunction in the arterial wall tissues followed by the development of atherosclerotic plaque. There are 3 main connexins expressed in human cardiovascular system: Cx37, Cx40, and Cx43. Alterations in the arterial wall cells observed in atherosclerosis include changes in the expression pattern of the main connexins and impairment of intercellular contacts and communication. According to the currently available data, Cx37 and Cx40 have anti-atherogenic and vasculoprotective properties, while Cx43 appears to be more pro-atherogenic. However, the effects of connexins are cell type-dependent and in many cases, remain to be studied in detail. In this review, we summarize the available knowledge on connexins of the arterial wall cells involved in atherosclerosis development.

Mitochondrial Signaling in Hypoxia

This paper focuses on a bioenergetic mechanism responding to hypoxia. This response involves hypoxia-induced reprogramming of respiratory chain function and switching from oxidation of complex I (NAD-related substrates) to complex II (succinate oxidation). Transient, reversible, compensatory activation of respiratory chain complex II is a major mechanism of urgent adaptation to hypoxia, which is necessary for 1) succinate-related energy synthesis in the conditions of oxygen shortage and formation of urgent resistance;2) succinate-related stabilization of HIF-1α and initiation of its transcriptional activity related with formation of long-term adaptation;3) succinate-dependent activation of the succinate-specific receptor GPR91. Thus, mitochondria perform a signaling function with succinate as a signaling molecule. Effects of succinate in hypoxia occur at three levels, intramitochondrial, intracellular and intercellular. In these settings, succinate displays antihypoxic activity. The review is focused on tactics and strategy for development of the antihypoxic defense and antihypoxants with energotropic properties.

Mitochondrial Signaling in Hypoxia

This paper focuses on a bioenergetic mechanism responding to hypoxia. This response involves hypoxia-induced reprogramming of respiratory chain function and switching from oxidation of complex I (NAD-related substrates) to complex II (succinate oxidation). Transient, reversible, compensatory activation of respiratory chain complex II is a major mechanism of urgent adaptation to hypoxia, which is necessary for 1) succinate-related energy synthesis in the conditions of oxygen shortage and formation of urgent resistance;2) succinate-related stabilization of HIF-1α and initiation of its transcriptional activity related with formation of long-term adaptation;3) succinate-dependent activation of the succinate-specific receptor GPR91. Thus, mitochondria perform a signaling function with succinate as a signaling molecule. Effects of succinate in hypoxia occur at three levels, intramitochondrial, intracellular and intercellular. In these settings, succinate displays antihypoxic activitie. The review is focused on tactics and strategy for development of the antihypoxic defense and antihypoxants with energotropic properties.

A study of the effects of 3,5-diiodo-L-thyronine in the tail suspension and forced swim models of depression

Objectives: Recent findings have further highlighted the role of the thyroid system in the pathophysiology of depression and revealed new physiologically relevant elements of the thyroid system. Our previous study showed an antidepressant-like effect of 3,5-diiodo-L-thyronine(T2), which was previously considered to be a physiologically inactive molecule, in mice. Here, we aimed to investigate the antidepressant-like effects of T2 further. Methods: We studied the effects of bolus injections of T2 to C57Bl6 J mice at doses of 0.25 or 0.75 mg/kg with the tail suspension and forced swim models. The effects of the higher dose were investigated in CD1 mice in the forced swim test. Potential behavioral effects of these treatments were also studied using the novel cage and dark-light box tests.Results: A reduction of depressive-like behavior was found in mice treated with 0.75 mg/kg of T2 in the tail suspension test, but not in the forced swim test. Locomotion and anxiety variables were unaltered following treatment with T2. There were no significant changes after bolus administration of 0.25 mg/kg T2 in either test for depressive-like behavior. Thus, bolus injection of T2 at the dose 0.75 mg/kg can induce antidepressant-like effects without affecting other behaviors. Conclusions: A discrepant result in the forced swim test may be due to its different sensitivity to T2 compared with the tail suspension paradigm. Furthermore, the development of procedural modifications of this model can be useful in its application in pre-clinical studies.

Behavioral features of mice fed with a cholesterol-enriched diet: Deficient novelty exploration and unaltered aggressive behavior

Objectives: Previous studies involving mice have demonstrated that a cholesterolenriched diet evokes liver steatosis, dystrophy, inflammation, and aspects of nonalcoholic fatty liver disease(NAFLD). These changes are accompanied by the activation of pro-inflammatory brain and liver molecular pathways, as well as anxiety and depressive-like behaviors. Given previously reported evidence for the neurobiological relationship between the above-mentioned molecular changes and abnormalities in coping with environmental stimuli, such as interactions with other individuals and new environmental contexts, we hypothesized that novelty exploration and aggressive behavior are affected in a mouse NAFLD model. Methods: To test this hypothesis, young female C57BL/6J mice were fed with a regular chow or a diet containing 0.2% cholesterol for 3 weeks. The mice were then assessed for new object and novel cage exploration, and social interaction in a food competition test. Results: We found reduced object exploration in mice on the cholesterol-enriched diet. This reduction was not related to whether the new object was placed in an anxiogenic or non-anxiogenic environment. These changes were accompanied by diminished exploration of the new environment in a novel cage, and delayed approach to food after a period of food deprivation. Mice on the regular chow or cholesterolenriched diet showed no differences in aggressive behavior towards a counter-partner in a food competition test. Food intake and body weight did not differ between the groups, thus, excluding their potential as confounders in the measured behaviors. Conclusions: We conclude that a diet enriched with cholesterol reduces novelty exploration irrespective of the anxiogenic level of the environment and does not induce aggressive behavior in female mice.

GABA_A-Coupled Cl-/ HCO₃<sup style="margin-left:-10px">-</sup>-ATPase from Plasma Membrane of the Rat Brain: Role of HCO₃<sup style="margin-left:-10px">-</sup>in the Enzyme Activation

This work examines the influence of Cl- (2.5 - 125 mM) and HCO3- (2 - 30 mM) on the Cl-/HCO3- - ATPase complex of the neuronal membrane and this enzyme is a Cl--pump that is coupled to GABAA receptors. The greatest (44%) activating effect on the enzyme is found with HCO3- (20 - 30 mM), while the maximum activity occurs in the presence of a ratio of ~25 mM HCO3- /~5mM Cl-. Blockers of the GABAA receptor, namely bicuculline (10 - 50 μM) and picrotoxin (50 - 100 μM), inhibit this anion activation, whereas the HCO3- -ATPase activity is not sensitive to these ligands. Autoradiographic analysis of the spectrum of the partially purified enzyme phosphorylated with [γ-32P]ATP allowed us to distinguish three major 32P-labeled protein whose molecular weight are about 57, 53, and 48 kDa. In the presence of 5 mM Cl-/25mM HCO3- and 100 μM picrotoxin, the intensity of the phosphorylation of bands significantly decreased, thereby confirming the assumption about coupled of binding sites for anions and GABAA-ergic ligands. It was suggested scheme of Cl--transport through the plasma membrane by utilizing neuronal Cl-/ -HCO3- ATPase in the low (5 mM) Cl- and high (25 mM) HCO3- concentrations. The data demonstrated for the first time that the GABAA-coupled Cl-/ HCO3- -ATPase from rat brain neuronal membranes is maximally activated at a Cl-/HCO3- ratio of 1:5 and it remains stable at high concentrations of substrate and buffer.

Therapeutic effects of garlic in cardiovascular atherosclerotic disease

Garlic(Allium sativum) is a widely known medicinal plant, potential of which remains to be fully evaluated. Its wide-range beneficial effects appear to be relevant for treatment and prevention of atherosclerosis and related diseases. It is generally believed that garlic-based preparations are able to improve lipid profile in humans, inhibit cholesterol biosynthesis, suppress low density lipoprotein oxidation, modulate blood pressure, suppress platelet aggregation, lower plasma fibrinogen level and increase fibrinolytic activity, thus providing clinically relevant cardioprotective and anti-atherosclerotic effects. It is important to assess the level of evidence available for different protective effects of garlic and to understand the underlying mechanisms. This information will allow adequate integration of garlic-based preparations to clinical practice. In this review, we discuss the mechanisms of anti-atherosclerotic effects of garlic preparations, focusing on antihyperlipidemic, hypotensive, anti-platelet and direct anti-atherosclerotic activities of the medicinal plant. We also provide an overview of available meta-analyses and a number of clinical trials that assess the beneficial effects of garlic.