Fatty liver disease associated with obesity is an important medical problem and the mechanisms for lipid accumulation in hepatocytes are not fully elucidated yet. Recent findings indicate that mitochondria play an importan t role in this process. Our data on hepatocytes in which mitochondria are in contact with other cytosolic structures importan t for their function, extend observations obtained on isolated mitochondria and confirm inhibition of Complex I activity in hepatocytes isolated from rats fed by high fat diet (HFD) compared with controls fed by standard diet (STD). Furthermore we have found that HFD- hepatocytes are more sensitive to the peroxidative stress because under these conditions also Complex II activity is disturbed. Therefore in HFD animals decrease of Complex I activity cannot be compensated by Complex II substrates as in STD hepatocytes. Our data thus indicates that combination of HFD and peroxidative stress potentiates HFD damaging effect of mitochondria because both branches of the respiratory chain (NADH- and flavoprotein-dependent) are disturbed., T. Garnol ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Distension is a regular mechanical stimulus in gastrointestinal (GI) tract. This study was designed to investigate the effect of hypotonic stress on pacemaking activity and determine whether actin microfilament is involved in its mechanism in cultured murine intestinal interstitial cells of Cajal (ICCs) by using whole-cell patch-clamp and calcium imaging techniques. Hypotonic stress induced sustained inward holding current from the baseline to -650±110 pA and significantly decreased amplitudes of pacemaker current. Hypotonic stress increased the intensity of basal fluorescence ratio (F/F0) from baseline to 1.09±0.03 and significantly increased Ca2+ oscillation amplitude. Cytochalasin-B (20 μM), a disruptor of actin microfilaments, significantly suppressed the amplitudes of pacemaker currents and calcium oscillations, respectively. Cytochalasin-B also blocked hypotonic stress-induced sustained inward holding current and hypotonic stress-induced increase of calcium oscillations. Phalloidin (20 μM), a stabilizer of actin microfilaments, significantly enhanced the amplitudes of pacemaker currents and calcium oscillations, respectively. Despite the presence of phalloidin, hypotonic stress was still able to induce an inward holding current and increased the basal fluorescence intensity. These results suggest that hypotonic stress induces sustained inward holding current via actin microfilaments and the process is mediated by alteration of intracellular basal calcium concentration and calcium oscillation in cultured intestinal ICCs., Z. Y. Wang, X. Huang, D. H. Liu, H. L. Lu, Y. C. Kim, W. X. Xu., and Obsahuje bibliografii
The aim of the present study was to define the stress-induced pattern of cytosolic glucocorticoid receptor (GR) and Hsp70 protein in the liver of male Wistar rats exposed to different stress models: acute (2 h/day) immobilization or cold (4 °C); chronic (21 days) isolation, crowding, swimming or isolation plus swimming and combined (chronic plus acute stress). Changes in plasma levels of corticosterone were studied by radioimmunoassay (RIA). The results obtained by Western immunoblotting showed that both acute stressors led to a significant decrease in cytosolic GR and Hsp70 levels. Compared to acute stress effects, only a weak decrease in the levels of GR and Hsp70 was demonstrated in chronic stress models. Chronically stressed rats, which were subsequently exposed to novel acute stressors (immobilization or cold), showed a lower extent of GR down-regulation when compared to acute stress. The exception was swimming, which partially restores this down-regulation. The observed changes in the levels of these major stress-related cellular proteins in liver cytosol lead to the conclusion that chronic stressors compromise intracellular GR down-regulation in the liver., D. Filipović, L. Gavrilović, S. Dronjak, M. Demajo, M. B. Radojčić., and Obsahuje bibliografii a bibliografické odkazy
Cardiovascular dynamic and variability data are commonly used in experimental protocols involving cognitive challenge. Usually, the analysis is based on a sometimes more and sometimes less well motivated single specific time resolution ranging from a few seconds to several minutes. The present paper aimed at investigating in detail the impact of different time resolutions of the cardiovascular data on the interpretation of effects. We compared three template tasks involving varying types of challenge, in order to provide a case study of specific effects and combinations of effects over different time frames and using different time resolutions. Averaged values of hemodynamic variables across an entire protocol confirmed typical findings regarding the effects of mental challenge and social observation. However, the hemodynamic response also incorporates transient variations in variables reflecting important features of the control system response. The fine-grained analysis of the transient behavior of hemodynamic variables demonstrates that information that is important for interpreting effects may be lost when only average values over the entire protocol are used as a representative of the system response. The study provides useful indications of how cardiovascular measures may be fruitfully used in experiments involving cognitive demands, allowing inferences on the physiological processes underlying the responses., H. K. Lackner, J. J. Batzel, A. Rössler, H. Hinghofer-Szalkay, I. Papousek., and Obsahuje bibliografii
The reactions of human organism to changes of internal or external environment termed as stress response have been at the center of interest during recent decades. Several theories were designed to describe the regulatory mechanisms which maintain the stability of vital physiological functions under conditions of threat or other environmental challenges. However, most of the models of stress reactivity were focused on specific aspects of the regulatory outcomes - physiological (e.g. neuroendocrine), psychological or behavioral regulation. Recently, a novel complex theory based on evolutionary and developmental biology has been introduced. The Adaptive Calibration Model of stress response employs a broad range of the findings from previous theories of stress and analyzes the responsivity to stress with respect to interindividual differences as a consequence of conditional adaptation - the ability to modify developmental trajectory to match the conditions of the social and physical environment. This review summarizes the contributions of the most important models in the field of stress response and emphasizes the importance of complex analysis of the psycho-physiological mechanisms. Moreover, it outlines the implications for nonpharmacological treatment of stress-related disorders with the application of biofeedback training as a promising tool based on voluntary modification of neurophysiological functions., I. Tonhajzerova, M. Mestanik., and Obsahuje bibliografii
Stress exposure activates the sympathoneural system, resulting in catecholamine release. Chronic stress is associated with development of numerous disorders, including cardiovascular diseases. Here we investigated the expression of mRNAs for catecholamine biosynthetic enzymes tyrosine-hydroxylase, dopamine-ß-hydroxylase and phenylethanolamine N-methyl- transferase, and for ß1- and ß2-adrenoceptors in the right and left ventricles of rats exposed to chronic unpredictable mild stress. The tyrosine-hydroxylase and dopamine-ß-hydroxylase mRNA levels were not affected by stress, whereas the phenylethanolamine N-methyltransferase mRNA levels significantly increased in both right and left ventricles. No changes in ß1-adrenoceptor mRNA levels in either right or left ventricles were observed. At the same time, stress produced a significant increase of β2-adrenoceptor mRNA levels in left ventricles. These results suggest that elevated expression of phenylethanolamine N-methyltransferase in both ventricules and ß2-adrenoceptor genes in left ventricles could provide a molecular mechanism that leads to altered physiological response, which is important for the organism coping with stress., N. Spasojevic, L. Gavrilovic, S. Dronjak., and Obsahuje bibliografii a bibliografické odkazy
In this study, we tested the hypothesis that experimental stress induces a specific change of left-right electrodermal activity (EDA) coupling pattern, as indexed by pointwise transinformation (PTI). Further, we hypothesized that this change is associated with scores on psychometric measures of the chronic stress-related psychopathology. Ninety-nine university students underwent bilateral measurement of EDA during rest and stress-inducing Stroop test and completed a battery of self-report measures of chronic stress-related psychopathology. A significant decrease in the mean PTI value was the prevalent response to the stress conditions. No association between chronic stress and PTI was found. Raw scores of psychometric measures of stress-related psychopathology had no effect on either the resting levels of PTI or the amount of stress-induced PTI change. In summary, acute stress alters the level of coupling pattern of cortico-autonomic influences on the left and right sympathetic pathways to the palmar sweat glands. Different results obtained using the PTI, EDA laterality coefficient, and skin conductance level also show that the PTI algorithm represents a ne w analytical approach to EDA asymmetry description., M. Světlák ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
This study was designed to investigate effect of alpha-lipoic acid (LA) on lipid peroxidation, nitric oxide production and antioxidant systems in rats exposed to chronic restraint stress. Twenty four male Wistar rats, aged three months, were divided into four groups: control (C), the group treated with LA (L), the group exposed to restraint stress (S) and the group exposed to stress and treated with LA (LS). Restraint stress was applied for 21 days (1 h/day) and LA (100 mg/kg/day) was injected intraperitonally to the L and LS groups for the same period. Restraint stress significantly decreased brain copper/zinc superoxide dismutase (Cu,Zn-SOD) and brain and retina glutathione peroxidase (GSH-Px) and catalase (CAT) activities compared with the control group. Thiobarbituric acid reactive substances (TBARS), nitrite and nitrate levels were significantly increased in the tissues of the S group compared with the C group. LA produced a significant decrease in brain and retina TBARS, nitrite and nitrate levels of the L and LS groups compared to their corresponding control groups. LA increased all enzyme activities in the tissues of the LS group compared to the S group. Our study indicated that LA is an ideal antioxidant candidate for the prevention of stress-induced lipid peroxidation., D. Akpinar, P. Yargiçoğlu, N. Derin, Y. Alicigüzel, A. Ağar., and Obsahuje bibliografii a bibliografické odkazy
a1_The genes that cause or increase susceptibility to essential hypertension (EH) and related an imal models remain unknown. Their identification is unlikely to be realized with current genetic approaches, because of ambiguities in the genotype-phenotype relationships in these polygenic disorders. In turn, the phenotype is not just an aggregate of traits, but needs to be related to specific components of the circulatory control system at different stages of EH. Hence, clues about important genes must come through the phenotype, reversing the order of current approaches. A recent systems analysis has highlighted major differences in circulatory control in the two main syndromes of EH: 1) stress-and-salt-related EH (SSR-EH) - a constrictor hypertension with low blood volume; 2) hypertensive obesity - SSR-EH plus obesity. Each is initiated through sensitization of central synapses linking the cerebral cortex to the hypothalamic defense area. Several mechanis ms are probably involved, including cerebellar effects on baroreflexes. The result is a sustained increase in sympathetic neural activity at stimulus levels that have no effect in normal subjects. Subsequent progression of EH is largely thro ugh interactions with non-neural mechanisms, including changes in concentration of vascular autacoids (e.g. nitric oxide) and the amplifying effect of structural changes in large resistance vessels. The rising vasoconstriction increases heterogeneity of blood flow, causing rarefaction (decreased microvascular densit y) and deterioration of vital organs. SSR-EH also increases food intake in response to stress, but only 40% of these individual s develop hypertensive obesity. Their brain ignores the adiposity signals that normally reduce eating., a2_Hyperinsulinemia masks the sympathetic vasoconstriction through its dilator action, rais es blood volume, whilst renal nephropathy and other diabetic complications are common. In each syndrome the neural and non-neural determinants of hypertension provide targets fo r identifying high BP genes. Reading the genome from the phenotype will require new approaches, such as those used in developmental genetics. In addition, transgenic technology may help verify hypotheses and examine whether an observed effect is through single or multiple mechanisms. To obtain answers will require substantial collaborative efforts between physiologists and geneticists., P. I. Korner., and Obsahuje bibliografii
Numerous hypotheses have been proposed about the pathogenesis of the polycystic ovarian syndrome (PCOS). However, hormonal control of persistent follicles has not be enestablished. The objective of the present study was to compare the follicular structure and hormonal profiles of rats treated with the adrenocor ticotrophic hormone (ACTH) with two experimental models of PCOS. ACTH-treated animals were compared with those exposed to continuous light, those treated with estradiol valerate, and with control (in proestrous and diestrous). Serum hormone levels, histomorphometrical changes, and immunoexpression of vimentin, cytokeratins, cadherins, and proliferating cell nuclear antigen (PCNA) were examined. Treatment with ACTH resulted in an elevation of corticosterone secretion with LH reduction but without changes in ovarian morphology. Although stress (or ACTH) stimulation may be only one of pathophysiological mechanisms involved in follicular cystathogenesis in other species, we do not have important evidence to suppose that this would happen in rats., C. Bavaralle, N. R. Salvetti, G. A. Mira, J. A. Lorente, H. H. Ortega., and Obsahuje bibliografii a bibliografické odkazy