Effect of ovariectomy on cardiac gene expression: inflammation and changes in SOCS gene expression.

Basic research on estrogen-related changes in cardiomyocyte gene expression is needed to provide a greater understanding of the effects of estrogen, so that hormone replacement trials and treatment can be based on a true comprehension of estrogen's pleiotropic effects. Therefore, we compared gene expression in models of estrogen depletion and estrogen replacement. Using gene expression array analysis, we examined differences in expression in cardiac tissue from ovariectomized (OVX), ovariectomized with 17beta-estradiol replacement (OVX/E2), and intact rats undergoing sham procedures (Sham). We found that OVX results in at least twofold changes in expression of genes involved in inflammation, vascular tone, apoptosis, and proteolysis compared with OVX/E2. With confirmation via real-time PCR, we found an OVX-induced increase in genes mediating inflammation (inhibin betaa, IL-6, TNF-alpha, SOCS2, SOCS3), an OVX-related decrease in the myocardial mRNA expression of genes involved in regulating vasodilation (endothelial NOS, soluble guanyl cyclase), an OVX-associated increase in extracellular matrix genes (collagen12alpha1, connexin 43), and an OVX-related increase in proapoptotic genes (caspase 3, calpain). Because details of cardiac signaling by SOCS genes are virtually unknown, we examined the protein expression for these genes via Western analyses. Although we observed OVX-related increases in SOCS2 and SOCS3 mRNA, SOCS2 and SOCS3 protein did not differ among groups. In light of these findings, investigation into the net effect of OVX on inflammation is warranted. These experiments add to existing evidence that estrogen can protect against negative changes associated with estrogen removal.     

Altered cardiac tissue gene expression during acute hypoxic exposure

Summary Anoxia has been shown to induce the expression of one or more stress proteins in mammalian cells and tissues. A less severe form of oxygen depletion, hypoxic hypoxia, occurs in response to hypobaric decompression which simulates high altitude conditions. Under these conditions mouse hearts accumulate mRNAs for at least two polypeptides at substantially elevated levels. The molecular weights of these proteins, 85 kDa and 95 kDa, are similar to those reported for other mammalian stress proteins or glucose-regulated proteins. Time course experiments suggest that mRNAs for these species increase continuously for up to 16 hours of treatment, while mRNA for 71 kDa and 79 kDa polypeptides are elevated early in the treatment, but later decrease to control values. Total heart mRNA template activity is also increased by the hypobaric treatment. These results demonstrate that mouse cardiac tissue is capable of mounting a cellular stress-like response when exposed to moderately stressful conditions. It also provides a model for studying the direct effects of acute hypoxic stress on cellular gene expression, and its relationship to physiological adaptation.     

Effect of chronic administration of doxorubicin on cardiac adenylate cyclase activity in mice

Cardiac adenylate cyclase activity was examined in mice treated chronically with doxorubicin. Mice received a subcutaneous dose of either 2 or 4 mg/kg doxorubicin twice weekly for 5 weeks. Mice were sacrificed five weeks after the last injection. Basal cardiac adenylate cyclase activity was significantly elevated in both the 2 and 4 mg/kg DXR-treated groups over the control level. GTP, isoproterenol (plus GTP), NaF, and forskolin stimulated activities in both the 2 and 4 mg/kg DXR-treated groups were also significantly elevated over control levels.     

Effect of acute and chronic vanadate administration on sugar transport in rat jejunum

Vanadate is known to have an insulin-like action which stimulates sugar transport in some systems like adipocytes and muscle cells, but in other systems it inhibits sugar transport by decreasing the activity of (Na+ +K+)-ATPase. To evaluate whether these two opposing actions may influence sugar transport across the intestine, we studied the effects of acute and chronic vanadate administration on the uptake of glucose, galactose, and 3-O-methylglucose in isolated rat intestinal cells. The sugar uptake measurements were also coupled by determinations of rubidium-86 uptake as a measure of the activity of the Na-K pump. Both acute and chronic vanadate administration reduced rubidium uptake by the cells but the reduction did not uniformly influence the uptake of the three sugars in question which were stimulated by the acute exposure of the cells to vanadate. Glucose uptake was also stimulated by chronic vanadate administration, but the uptakes of galactose and 3-O-methylglucose were respectively unaffected or inhibited by chronic vanadate. The findings suggest that the effect of vanadate on sugar transport is dependent on the net difference between two actions of vanadate: (i) stimulation of a receptor site (possibly an insulin receptor site) in the intestinal cell membrane and (ii) inhibition of the Na-K pump. During acute vanadate exposure, the stimulation of the receptor site was very likely a dominant feature which overwhelms the inhibition of the pump. Chronic exposure to vanadate led, on the other hand, to only a limited degree of stimulation of the receptor site and the inhibition of the Na-K pump became evident in the uptake measurements of galactose and 3-O-methyl-glucose. Glucose uptake, however, was stimulated by chronic vanadate ingestion due, very likely, to an increase in the metabolism of this sugar which occurred only with prolonged exposure of the rat intestine to vanadate.     

Effect of acute and chronic cardiac denervation on osmotic release of vasotocin in chickens

Hypo- and hyperosmotic NaCl were infused intravenously to examine osmotic release of arginine vasotocin (AVT) in anesthetized, acutely cardiac-denervated chickens and in conscious, chronically denervated birds. Mean arterial blood pressure was consistently higher in denervated compared to sham-operated chickens but heart rates were similar in experimental and control groups. Plasma AVT concentrations (pAVT) were significantly higher than controls in acutely, but not chronically, denervated chickens. The slope of the regression line relating pAVT to plasma sodium concentration was higher in denervated birds indicating that removal of cardiac receptor activity increases the osmotic sensitivity of the AVT system. The results suggest that cardiac end-net receptor activity may participate in the regulation of blood pressure and can modulate the release of antidiuretic hormone in the chicken.     

Effect of a cholecystokinin tetrapeptide analogue on opioid reception under acute and chronic morphine administration

Effects of a modified CCK-4, a tetrapeptide fragment of cholecystokinin, on opioid reception and cAMP level were studied. The modified CCK-4 changed the ligand binding of the opioid receptors of μ-and δ-types in vitro. In vivo, it prevented changes in opioid reception caused by an acute morphine administration or by morphine withdrawal after its long-term administration. The CCK-4 analogue did not exert any effect in the state of intoxication after a long-term administration of morphine or even promoted the morphine effect. The injection of the CCK-4 analogue alone or together with morphine changed the forskolin-stimulated level of cAMP. These changes depended on the brain structure and the duration of the administration of morphine and the CCK-4 analogue.     

Effect of a cholecystokinin tetrapeptide analogue on opioid reception under acute and chronic morphine administration

Effects of a modified CCK-4, a tetrapeptide fragment of cholecystokinin, on opioid reception and cAMP level were studied. The modified CCK-4 changed the ligand binding of the opioid receptors of mu- and sigma-types in vitro. In vivo, it prevented changes in opioid reception caused by a single morphine injection or by morphine withdrawal after its long-term introduction. The CCK-4 analogue did not exert any effect in the state of intoxication after a long-term introduction of morphine or even promoted the morphine effect. The introduction of the CCK-4 analogue alone or together with morphine changed the forskoline-stimulated level of cAMP. These changes depended on the brain structure and the duration of the introduction of morphine and the CCK-4 analogue. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.     

Correlation between cardiac oxidative stress and myocardial pathology due to acute and chronic norepinephrine administration in rats

BACKGROUND: To investigate the cardiotoxic role of reactive oxygen species (ROS) and of products derived from catecholamines auto-oxidation, we studied: (1) the response of antioxidant cardiac cellular defence systems to oxidative stress induced by norepinephrine (NE) administration, (2) the effect of NE administration on cardiac beta1-adrenergic receptors by means of receptor binding assay, (3) the cellular morphological alterations related to the biologically cross-talk between the NE administration and cytokines [tumor necrosis factor-alpha (TNF-alpha), monocyte chemotactic protein-1 (MCP-1), interleukins IL6, IL8, IL10]. METHODS AND RESULTS: A total of 195 male rats was used in the experiment. All animals underwent electrocardiogram (EKG) before being sacrificed. The results obtained show that NE administration influences the antioxidant cellular defence system significantly increasing glutathione peroxidase (GPx) activity, glutathione reductase (GR) and superoxide dismutase (SOD). The oxidized glutathione (GSH/GSSG) ratio significantly decreases and malondialdehyde (MDA) levels increase showing a state of lipoperoxidation of cardiac tissue. We describe a significant apoptotic process randomly sparse in the damaged myocardium and the effect of ROS on the NE-mediated TNF-alpha, MCP-1, and IL6, IL8, IL10 production. CONCLUSIONS: Our results support the hypothesis that catecholamines may induce oxidative damage through reactive intermediates resulting from their auto-oxidation, irrespective of their interaction with adrenergic receptors, thus representing an important factor in the pathogenesis of catecholamines-induced cardiotoxicity. The rise of the cardioinhibitory cytokines may be interpreted as the adaptive response of jeopardized myocardium with respect to the cardiac dysfunction resulting from NE injection.     

Effect of acute or chronic administration of caffeine on performance and on catecholamines during maximal cycle ergometer exercise

Seven men were studied during maximal cycle ergometer exercise, to assess the effects of a single or continuous caffeine ingestion on performance and catecholamine secretion. A single blind and randomised procedure was followed with three trials at 100 +/- 5% VO2 max until exhaustion. The first trial was performed after a single administration of 250 mg of caffeine (a). The second and third trials were performed after a treatment of 5 days with 250 mg caffeine per day (continuous = c) and after placebo (p). a and c caffeine administration, 60 min prior to exercise, did not significantly change the time to exhaustion, but increased the plasma levels of both epinephrine (E) and norepinephrine (NE) at exhaustion (p less than 0.05). Single ingestion of caffeine accelerated the elimination of E and NE and increased the maximal blood lactic acid. These data suggest that both single and continuous administration of caffeine do not enhance performance during maximal cycle ergometer exercise, but do increase the exercise response of catecholamine. Only a single administration modifies the blood lactate accumulation.     

Thyroid hormone metabolism and cardiac gene expression after acute myocardial infarction in the rat

In a rat model of acute myocardial infarction (MI) produced by coronary artery ligation, thyroid hormone metabolism was altered with significant reductions (54%) in serum triiodo-L-thyronine (T(3)), the cellular active hormone metabolite. T(3) has profound effects on the heart; therefore, rats were treated with T(3) after acute MI for 2 or 3 wk, at either replacement or elevated doses, to determine whether cardiac function and gene expression could be normalized. Acute MI resulted in a 50% (P < 0.001) decrease in percent ejection fraction (%EF) with a 32-35% increase (P < 0.01) in compensatory left ventricle (LV) hypertrophy. Treatment of the MI animals with either replacement or elevated doses of T(3) significantly increased %EF to 64 and 73% of control, respectively. Expression levels of several T(3)-responsive genes were altered in the hypertrophied LV after MI, including significant decreases in alpha-myosin heavy chain (MHC), sarcoplasmic reticulum calcium-activated ATPase (SERCA2), and Kv1.5 mRNA, whereas beta-MHC and phospholamban (PLB) mRNA were significantly increased. Normalization of serum T(3) did not restore expression of all T(3)-regulated genes, indicating altered T(3) responsiveness in the postinfarcted myocardium. Although beta-MHC and Kv1.5 mRNA content was returned to control levels, alpha-MHC and SERCA2 were unresponsive to T(3) at replacement doses, and only at higher doses of T(3) was alpha-MHC mRNA returned to control values. The present study showed that acute MI in the rat was associated with a fall in serum T(3) levels, LV dysfunction, and altered expression of T(3)-responsive genes and that T(3) treatment significantly improved cardiac function, with normalization of some, but not all, of the changes in gene expression.     

Effects of acute and chronic STZ-induced diabetes on clock gene expression and feeding in the gastrointestinal tract

This study aims to establish the antiproliferative effects of PK11195, a peripheral benzodiazepine receptor antagonist (PBR) in rat mammary tumor cells. Breast tumors were induced by administration of a carcinogen, dimethylbenz[a]anthracene to 50-day-old female rats maintained on a standard AIN-76A diet with casein as the protein source. The tumors were developed approximately after 120 days. The tumors were of grade I (20%), grade II (60%), and grade III (20%). The tumors were isolated and cultured in DMEM/F12 media with supplements. We characterized the properties of the isolated cells and study the effect of PK11195 on those cells. We were successful in growing breast tumor cells up to 30 passages for cellular characterization. These cells had high reactivity with Ki-67 and PCNA antibodies suggesting high proliferation rate. These cells were highly invasive as evident by matrigel invading ability. Furthermore, these cells acquired a positive response for CD-31 and VEGF antibodies suggesting angiogenic potential, and also possessed migrating ability/motility as evident by the wound healing properties. These cells expressed elevated levels of PBR, a cancer promoting gene. The proliferation, invasion and migration appear to decrease when treated with PK11195, a PBR antagonist. Furthermore, PK11195 treatment caused an increase in apoptosis as evident by increase in the levels of annexin V. However, the inhibition of cell proliferation by PK11195 was counteracted by Ro5-4864, a PBR agonist. Thus, PBR antagonist may be a potential therapeutic agent for the control of aggressiveness of breast cancer.     

The effects of zofenopril on cardiac function and pro-oxidative parameters in the streptozotocin-induced diabetic rat heart

Diabetes mellitus is a chronic condition that continues to increase in both incidence and prevalence. Renin–Angiotensin–Aldosterone System is one of the main modulators of chronic hyperglycaemia and, thus, its influence on tissues. Hyperglycaemia-induced oxidative stress is an important factor in diabetic cardiomyopathy. The present study was carried out on 24 adult male Wistar albino rats (8-week-old and with body masses of 190 ± 10 g). We evaluated the influence of acute administration of zofenopril on ex vivo myocardial function from rats with streptozotocin-induced diabetes mellitus, with a special emphasis on cardiodynamic and oxidative stress parameters in diabetic rat hearts. Rats were divided randomly into two groups (12 animals per group): control non-diabetic animals (C) were healthy rats perfused with 1.5 µM of zofenopril, and STZ-treated diabetic animals (DM) were diabetic animals perfused with 1.5 µM of zofenopril 4 weeks after the induction of diabetes. Our results demonstrated that diabetic rats are characterized by a depressed cardiac performance and that oxidative markers are related to alterations in cardiac function in rats with 4 weeks of STZ-induced diabetes. Additionally, the use of zofenopril as a monotherapy slightly diminished cardiac damage induced by chronic hyperglycaemia. However, long-term follow-up intervention trials are necessary to fully demonstrate the benefit of zofenopril in this context. A challenge for future investigations will be to identify the effects of chronic administration or combination therapy with angiotensin-converting enzyme inhibitors in various models of diabetes.     

Embryonic spontaneous motility after acute and chronic administration of kainate

Changes in spontaneous motility after the acute and chronic administration of kainate were studied in 11- to 19-day-old chick embryos. 1. After acute administration, kainate (20 mg/kg e.w.) already depressed motility in 11-day-old embryos. From the 17th day it induced explosive activation of embryonic motility, but never in chronic spinal preparations. 2. The chronic administration of kainate (2.56 +/- 0.62 mg/kg e.w./24 h) reduced embryonic motor activity. The effect already developed after administering kainate from the 4th to the 8th day of incubation. Prolonged administration made no important difference to the results. Chronic administration was followed by histopathological changes in the nervous tissue. These were mainly of an oedematous type and affected the glia and the brain capillaries, whereas pyknotic changes were found in the large neurones. 3. The results showed that the CNS is already sensitive to the neurotoxic effect of kainate from the early stages of embryogenesis and that the picture of the reaction of the embryonic CNS is closely correlated to the degree of maturation.     

CaGE: cardiac gene expression knowledgebase

CaGE is a Cardiac Gene Expression knowledgebase we have developed to facilitate the analysis of genes important to human cardiac function. CaGE integrates the functionality of the LocusLink database with data from several human cardiac expression libraries, phenotypic data from OMIM and data from large-scale microarray gene expression studies to create a knowledgebase of gene expression in human cardiac tissue. The knowledgebase is fully searchable via the web using several intuitive query interfaces. Results can be displayed in several concise easy to navigate formats. AVAILABILITY: CaGE is located at http://www.cage.wbmei.jhu.edu     

The effect of the acute and chronic administration of dalargin to mongrel rats on cardiac chronotropism at rest and under physical loading]

In chronic experiments on untrained awakening males of white rats it has been shown that the prolonged intraperitoneal injection of the opiate receptor agonist delargin (during 4, 5 days; 10 mkg/kg; twice a day) leads the chronotropic heart response to the maximum level of exercises and simultaneous decrease of heart rate variability. All this is accompanied by animals' undue fatiguability. It has been concluded that the chronic injection of opioid agonist receptors causes the decrease of sensitivity of these receptors to the action of endogenic opioids and as a consequence--the increase of sympathetic regulatory action on the heart rate at physical exercises and growth of fatiguability.