Vascular ATGL-dependent lipolysis and the activation of cPLA2-PGI2 pathway protect against postprandial endothelial dysfunction.

Adipose triglyceride lipase (ATGL) is involved in lipolysis and displays a detrimental pathophysiological role in cardio-metabolic diseases. However, the organo-protective effects of ATGL-induced lipolysis were also suggested. The aim of this work was to characterize the function of lipid droplets (LDs) and ATGL-induced lipolysis in the regulation of endothelial function. ATGL-dependent LDs hydrolysis and cytosolic phospholipase A2 (cPLA2)-derived eicosanoids production were studied in the aorta, endothelial and smooth muscle cells exposed to exogenous oleic acid (OA) or arachidonic acid (AA). Functional effects of ATGL-dependent lipolysis and subsequent activation of cPLA2/PGI2 pathway were also studied in vivo in relation to postprandial endothelial dysfunction.The formation of LDs was invariably associated with elevated production of endogenous AA-derived prostacyclin (PGI2). In the presence of the inhibitor of ATGL or the inhibitor of cytosolic phospholipase A2, the production of eicosanoids was reduced, with a concomitant increase in the number of LDs. OA administration impaired endothelial barrier integrity in vitro that was further impaired if OA was given together with ATGL inhibitor. Importantly, in vivo, olive oil induced postprandial endothelial dysfunction that was significantly deteriorated by ATGL inhibition, cPLA2 inhibition or by prostacyclin (IP) receptor blockade.In summary, vascular LDs formation induced by exogenous AA or OA was associated with ATGL- and cPLA2-dependent PGI2 production from endogenous AA. The inhibition of ATGL resulted in an impairment of endothelial barrier function in vitro. The inhibition of ATGL-cPLA2-PGI2 dependent pathway resulted in the deterioration of endothelial function upon exposure to olive oil in vivo. In conclusion, vascular ATGL-cPLA2-PGI2 dependent pathway activated by lipid overload and linked to LDs formation in endothelium and smooth muscle cells has a vasoprotective role by counterbalancing detrimental effects of lipid overload on endothelial function.

Aromatic sulphonamides of aziridine-2-carboxylic acid derivatives as novel PDIA1 and PDIA3 inhibitors.

In this study, we report a series of newly synthesised sulphonamides of aziridine-2-carboxylic acid (Az-COOH) ester and amide analogues as potent protein disulphide isomerase (PDI, EC 5.3.4.1) inhibitors. The inhibitory activity on PDI was determined against recombinant human PDIA1 and PDIA3 proteins using an insulin reduction assay. These compounds in low micromolar to low nanomolar concentrations showed the effective in vitro inhibitory properties of PDIA1 with weaker effects on PDIA3. Complexes of 15N- and 15N,13C- uniformly labelled recombinant human PDIA1a with two PDIA1 inhibitors were produced and investigated by a protein nuclear magnetic resonance (NMR) spectroscopy. It was found that both C53 and C56 of the PDIA1 enzyme were involved in covalent binding. Finally, in a range of pharmacological studies, we demonstrated that investigated compounds displayed anti-cancer and anti-thrombotic activity. These findings demonstrate that sulphonamides of Az-COOH derivatives are promising candidates for the development of novel anti-cancer and anti-thrombotic agents.

Characterization of age-dependent decline in spontaneous running performance in the heart failure Tgαq*44 mice.

In this study we characterize the impact of aging on the spontaneous running performance of the Tgαq*44 mice (transgenic murine model of chronic heart failure) as compared to the wild-type FVB mice. In 166 mice we have recorded the following parameters of their physical activities in the running wheels: the total distance covered during the experiment (Dsum), the maximal distance covered in single-effort (Dmax), mean time spent on running per 24 h (Tmean), mean running speed (νmean), the maximum instantaneous speed of run (νmax) and the number of efforts (i.e. the number of running events undertaken by the mice) during 54 days, in four age groups ~4, ~10, ~12 and ≥12.5 months of age. The level of spontaneous running performance of the FVB mice remained essentially unchanged, but a strong impact of aging in the Tgαq*44 mice on their running performance was found. Namely, the Dsum, Dmax, Tmean and νmean in the Tgαq*44 mice at the age of ≥12.5 months decreased by ~50%, when compared to its level corresponding level at the age of ~4 months, with far lesser effect of aging on their Vmax. Surprisingly, the number of attempts to perform running by the Tgαq*44 mice at the age of 4 - 12 months remained essentially unchanged. This suggests that the exercise intolerance of the aging heart failure (HF) mice seems to be more dependent on deterioration of heart and muscles function linked to HF than on a possible ageing-related impairment of the 'willngness' to initiate running, generated by the central nervous system.

Preservation of left ventricle peak and mean pulse flow blood velocity despite progressive deterioration of cardiac function in a chronic heart failure murine model.

The goal of this study was to assess the alterations in left ventricle (LV) blood flow velocity patterns in relation to progressive impairment of cardiac function in the course of heart failure (HF) in a unique murine model of chronic HF in Tgαq*44 mice. Doppler- and MRI-based assessments of blood velocity and cardiac performance, respectively, were performed in Tgαq*44 mice at the age of 1, 2, 4, 6, 8 and 12 months as compared with age-matched FVB control mice. One-month-old Tgαq*44 mice displayed elongated early diastolic phase with fully preserved cardiac function that, however, progressively deteriorated in older Tgαq*44 mice. As early as in 2-month-old Tgαq*44 mice, the filling rate (FR), max. radial strain and end-systolic volume increased; in 4-month-old Tgαq*44 mice, the ejection fraction, max. circ. strain and ventriculo-arterial coupling decreased, and the ejection time was prolonged; in 6 - 8-month-old Tgαq*44 mice, the stroke volume, max. (both) strains decreased, end-systolic volume, FR and end-diastolic volume increased, and finally, in 12-month-old Tgαq*44 mice, the ejection fraction, cardiac output and stroke volume were all severely impaired. In the early phase of HF development, no differences were observed in Tgαq*44 mice versus FVB mice regarding systolic LV flow pattern, but indices of mitral diastolic flow were considerably increased in 1-month-old Tgαq*44 mice versus FVB mice. In the late phase of HF, despite progressive deterioration of cardiac function, LV pulse flow blood velocity was not altered in Tgαq*44 mice up to the age of 8 months. Systolic peak velocity and mean acceleration time deteriorated only in 12-month-old Tgαq*44 mice, with peak acceleration and mean velocity values still preserved. We demonstrated that the cardiac mitral diastolic flow pattern displayed adaptive changes in the very early phase of HF development in Tgαq*44 mice and that these changes preceded early alterations in LV haemodynamics. Then, despite the progressive deterioration of cardiac haemodynamics, peak and mean in- and out-flow velocities remained unchanged for a relatively long time and deteriorated only at the end-stage HF. Altogether, we revealed that in addition to cardiac performance, adaptive vascular performance represents an important factor determining LV mitral inflow and ejection flow phenotype during the progression of chronic HF in Tgαq*44 mice.

Vibrational spectroscopy-based quantification of liver steatosis.

The liver plays a central role in lipid metabolism, and abnormal lipid accumulation in the liver is a key feature of Non-Alcoholic Fatty Liver Disease. In experimental studies, quantification of liver steatosis is commonly based on lipids staining or biochemical analysis. Here, we present a spectroscopic approach for quantitative analysis of the lipid content in the freeze-dried liver. The method is based on vibrational spectroscopy (Raman and infrared) measurements applied for Partial Least Squares (PLS) regression modeling. The obtained PLS models show a good correlation of the spectroscopic data with the reference histological evaluation of steatosis based on Oil Red O (ORO)-stained images of liver cross sections. Vibrational spectroscopy with PLS-based modeling described here represents a useful approach for the fast assessment of the liver steatosis in a small sample of freeze-dried liver tissue. In conclusion, our work demonstrates the easy-to-use method that can be applied in laboratory routine as a beneficial alternative to the established ORO staining.

Eicosanoid profiling in effluent of isolated perfused heart of Tgαq*44 mice with advanced heart failure.

A plethora of studies have suggested the involvement of various eicosanoids in heart failure. The aim of this study was to profile eicosanoid release from isolated murine heart at transition and end-stage phases of heart failure (HF) in Tgαq*44 mice as compared with age-matched wild-type FVB mice. Using an UPLC-MS/MS-based method, the concentration of selected eicosanoids was measured in cardiac effluents collected from isolated perfused mice hearts according to the Langendorff technique in Tgαq*44 and FVB mice (8- and 12-month-old) in basal conditions and in response to bolus injection of arachidonic acid (AA), a major substrate for eicosanoids. In basal conditions, only some eicosanoids were detected in the coronary effluents, with 6-keto-PGF1α, PGD2, 12-HETE detected at the highest concentration. In response to AA, a wide range of its metabolites was detected, including not only prostanoids and HETEs, but also EETs and DHETs. Cardiac production of 6-keto-PGF1α, PGD2, PGE2, PGF2α, TXB2 in basal conditions was unchanged at the transition phase of HF, whereas it was increased at the end-stage of disease in Tgαq*44 mice as compared with age-matched FVB mice. In response to AA, the synthesis of PGE2, 12-, 15-HETEs, 8,9-, 11,12-DHETs were also elevated at the end-stage phase of HF in Tgαq*44 mice as compared to healthy animals. AA-induced vasodilation effect was greater at the end-stage phase of HF in Tgαq*44 mice as compared with age-matched FVB mice, but it was not changed at the transition phase of the disease. In conclusion, eicosanoid profiling in isolated perfused heart pointed to PGI2, PGD2 and 12-HETE as the most abundant AA metabolites of the isolated murine heart. In Tgαq*44 mice, the end-stage phase of heart failure was accompanied by major activation of cyclooxygenase pathways (PGI2, TXA2, PGD2, PGE2, PGF2α), 8,9-, 11,12-EET/DHETs pathways and 12-, 15-HETEs pathways in the heart.

Alterations in NO- and PGI2- dependent function in aorta in the orthotopic murine model of metastatic 4T1 breast cancer: relationship with pulmonary endothelial dysfunction and systemic inflammation.

BACKGROUND: Patients with cancer develop endothelial dysfunction and subsequently display a higher risk of cardiovascular events. The aim of the present work was to examine changes in nitric oxide (NO)- and prostacyclin (PGI2)-dependent endothelial function in the systemic conduit artery (aorta), in relation to the formation of lung metastases and to local and systemic inflammation in a murine orthotopic model of metastatic breast cancer. METHODS: BALB/c female mice were orthotopically inoculated with 4T1 breast cancer cells. Development of lung metastases, lung inflammation, changes in blood count, systemic inflammatory response (e.g. SAA, SAP and IL-6), as well as changes in NO- and PGI2-dependent endothelial function in the aorta, were examined 2, 4, 5 and 6 weeks following cancer cell transplantation. RESULTS: As early as 2 weeks following transplantation of breast cancer cells, in the early metastatic stage, lungs displayed histopathological signs of inflammation, NO production was impaired and nitrosylhemoglobin concentration in plasma was decreased. After 4 to 6 weeks, along with metastatic development, progressive leukocytosis and systemic inflammation (as seen through increased SAA, SAP, haptoglobin and IL-6 plasma concentrations) were observed. Six weeks following cancer cell inoculation, but not earlier, endothelial dysfunction in aorta was detected; this involved a decrease in basal NO production and a decrease in NO-dependent vasodilatation, that was associated with a compensatory increase in cyclooxygenase-2 (COX-2)- derived PGI2 production. CONCLUSIONS: In 4 T1 metastatic breast cancer in mice early pulmonary metastasis was correlated with lung inflammation, with an early decrease in pulmonary as well as systemic NO availability. Late metastasis was associated with robust, cancer-related, systemic inflammation and impairment of NO-dependent endothelial function in the aorta that was associated with compensatory upregulation of the COX-2-derived PGI2 pathway.

Differential effects of nitric oxide deficiency on primary tumour growth, pulmonary metastasis and prostacyclin/thromboxane A2 balance in orthotopic and intravenous murine models of 4T1 breast cancer.

The role of nitric oxide (NO) in tumour progression and metastasis is not clear, therefore the present work aimed to better characterise the effects of nitric oxide synthase (NOS) inhibition by L-Nω-nitroarginine methyl ester (L-NAME) on primary tumour growth, pulmonary metastasis, inflammatory state and prostacyclin (PGI2)/thromboxane A2 (TXA2) balance in a 4T1 murine model of breast cancer. To distinguish effects of NO deficiency on disease development, 4T1 cancer cells were administered orthotopically or intravenously to Balb/c mice. The systemic NO bioavailability, pulmonary inflammation and plasma levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1α (6-keto-PGF1α) were assessed. The study shows that, in the orthotopic model of 4T1 breast cancer, L-NAME hampered primary tumour growth, reduced pulmonary metastases, delayed inflammatory response but did not alter biosynthesis of TXB2 and 6-keto-PGF1α as well as PGI2/TXA2 ratio in cancer-bearing mice. Interestingly, in the intravenous model of 4T1 breast cancer, NOS inhibition did not influence metastasis nor inflammation, but it increased both TXB2 and 6-keto-PGF1α biosynthesis without affecting PGI2/TXA2 ratio. In conclusion, in a 4T1 murine model of metastatic breast cancer, NO plays a major role in primary tumour development, while NO is not the key mediator of cancer cell extravasation to the lungs. Furthermore, NO-deficiency activates a PGI2-dependent compensatory mechanism only in the intravenous model of 4T1 breast cancer.

Atomic Force Microscopy Reveals the Dynamic Morphology of Fenestrations in Live Liver Sinusoidal Endothelial Cells.

Here, we report an atomic force microscopy (AFM)-based imaging method for resolving the fine nanostructures (e.g., fenestrations) in the membranes of live primary murine liver sinusoidal endothelial cells (LSECs). From data on topographical and nanomechanical properties of the selected cell areas collected within 1 min, we traced the dynamic rearrangement of the cell actin cytoskeleton connected with the formation or closing of cell fenestrations, both in non-stimulated LSECs as well as in response to cytochalasin B and antimycin A. In conclusion, AFM-based imaging permitted the near real-time measurements of dynamic changes in fenestrations in live LSECs.

Morphology and force probing of primary murine liver sinusoidal endothelial cells.

Liver sinusoidal endothelial cells (LSECs) represent unique type of endothelial cells featured by their characteristic morphology, ie, lack of a basement membrane and presence of fenestrations-transmembrane pores acting as a dynamic filter between the vascular space and the liver parenchyma. Delicate structure of LSECs membrane combined with a submicron size of fenestrations hinders their visualization in live cells. In this work, we apply atomic force microscopy contact mode to characterize fenestrations in LSECs. We reveal the structure of fenestrations in live LSECs. Moreover, we show that the high-resolution imaging of fenestrations is possible for the glutaraldehyde-fixed LSECs. Finally, thorough information about the morphology of LSECs including great contrast in visualization of sieve plates and fenestrations is provided using Force Modulation mode. We show also the ability to precisely localize the cell nuclei in fixed LSECs. It can be helpful for more precise description of nanomechanical properties of cell nuclei using atomic force microscopy. Presented methodology combining high-quality imaging of fixed cells with an additional nanomechanical information of both live and fixed LSECs provides a unique approach to study LSECs morphology and nanomechanics that could foster understanding of the role of LSECs in maintaining liver homeostasis.

Effects of a single bout of strenuous exercise on platelet activation in female ApoE/LDLR-/- mice.

Strenuous physical exercise leads to platelet activation that is normally counterbalanced by the production of endothelium-derived anti-platelet mediators, including prostacyclin (PGI2) and nitric oxide (NO). However, in the case of endothelial dysfunction, e.g. in atherosclerosis, there exists an increased risk for intravascular thrombosis during exercise that might be due to an impairment in endothelial anti-platelet mechanisms. In the present work, we evaluated platelet activation at rest and following a single bout of strenuous treadmill exercise in female ApoE/LDLR-/- mice with early (3-month-old) and advanced (7-month-old) atherosclerosis compared to female age-matched WT mice. In sedentary and post-exercise groups of animals, we analyzed TXB2 generation and the expression of platelet activation markers in the whole blood ex vivo assay. We also measured pre- and post-exercise plasma concentration of 6-keto-PGF1α, nitrite/nitrate, lipid profile, and blood cell count. Sedentary 3- and 7-month-old ApoE/LDLR-/- mice displayed significantly higher activation of platelets compared to age-matched wild-type (WT) mice, as evidenced by increased TXB2 production, expression of P-selectin, and activation of GPIIb/IIIa receptors, as well as increased fibrinogen and von Willebrand factor (vWf) binding. Interestingly, in ApoE/LDLR-/- but not in WT mice, strenuous exercise partially inhibited TXB2 production, the expression of activated GPIIb/IIIa receptors, and fibrinogen binding, with no effect on the P-selectin expression and vWf binding. Post-exercise down-regulation of the activated GPIIb/IIIa receptor expression and fibrinogen binding was not significantly different between 3- and 7-month-old ApoE/LDLR-/- mice; however, only 7-month-old ApoE/LDLR-/- mice showed lower TXB2 production after exercise. In female 4-6-month-old ApoE/LDLR-/- but not in WT mice, an elevated pre- and post-exercise plasma concentration of 6-keto-PGF1α was observed. In turn, the pre- and post-exercise plasma concentrations of nitrite (NO2-) and nitrate (NO3-) were decreased in ApoE/LDLR-/- as compared to that in age-matched WT mice. In conclusion, we demonstrated overactivation of platelets in ApoE/LDLR-/- as compared to WT mice. However, platelet activation in ApoE/LDLR-/- mice was not further increased by strenuous exercise, but was instead attenuated, a phenomenon not observed in WT mice. This phenomenon could be linked to compensatory up-regulation of PGI2-dependent anti-platelet mechanisms in ApoE/LDLR-/- mice.

Label-free spectroscopic characterization of live liver sinusoidal endothelial cells (LSECs) isolated from the murine liver.

Liver sinusoidal endothelial cells (LSECs) represent a highly specialized and unique type of endothelial cell in terms of their morphology and function. The biochemical and functional characterization of LSECs in vitro is restrained by the rapid change of LSECs' phenotype upon culturing under classical experimental conditions. In this work, we present a novel approach to characterize the biochemical content of murine LSECs, freshly isolated from the liver, with the use of microspectroscopic analysis. For comparison, hepatocytes and Hepatic Stellate Cells (HSCs) were analyzed. Our approach, based on label-free confocal Raman imaging of live cells combined with chemometric analysis, provided insight into the biochemical content of freshly isolated LSECs on a subcellular level. LSECs were featured by a distinct biochemical signature in comparison with other major cell types of the liver. Based on our work we claim that the non-invasive and non-destructive confocal Raman imaging may assist in obtaining chemical information spatially distributed within the cells that characterize the phenotype of primary LSECs as well as other types of liver cells. Furthermore, our approach provides a unique insight into LSECs' morphology and chemical composition that may help to understand their functions.

Effects of chronic nitric oxide synthase inhibition on V'O2max and exercise capacity in mice.

Acute inhibition of NOS by L-NAME (Nω-nitro-L-arginine methyl ester) is known to decrease maximal oxygen consumption (V'O2max) and impair maximal exercise capacity, whereas the effects of chronic L-NAME treatment on V'O2max and exercise performance have not been studied so far. In this study, we analysed the effect of L-NAME treatment, (LN2 and LN12, respectively) on V'O2max and exercise capacity (in maximal incremental running and prolonged sub-maximal incremental running tests), systemic NO bioavailability (plasma nitrite (NO2-) and nitrate (NO3-)) and prostacyclin (PGI2) production in C57BL6/J mice. Mice treated with L-NAME for 2 weeks (LN2) displayed higher V'O2max and better running capacity than age-matched control mice. In LN2 mice, NO bioavailability was preserved, as evidenced by maintained NO2- plasma concentration. PGI2 production was activated (increased 6-keto-PGF1α plasma concentration) and the number of circulating erythrocytes (RBC) and haemoglobin concentration were increased. In mice treated with L-NAME for 12 weeks (LN12), NO bioavailability was decreased (lower NO2- plasma concentration), and 6-keto-PGF1α plasma concentration and RBC number were not elevated compared to age-matched control mice. However, LN12 mice still performed better during the maximal incremental running test despite having lower V'O2max. Interestingly, the LN12 mice showed poorer running capacity during the prolonged sub-maximal incremental running test. To conclude, short-term (2 weeks) but not long-term (12 weeks) treatment with L-NAME activated robust compensatory mechanisms involving preservation of NO2- plasma concentration, overproduction of PGI2 and increased number of RBCs, which might explain the fully preserved exercise capacity despite the inhibition of NOS.

Short-term treatment with nitrate is not sufficient to induce in vivo antithrombotic effects in rats and mice.

In humans, short-term supplementation with nitrate is hypotensive and inhibits platelet aggregation via an nitric oxide (NO)-dependent mechanism. In the present work, we analyzed whether short-term treatment with nitrate induces antithrombotic effects in rats and mice. Arterial thrombosis was evoked electrically in a rat model in which renovascular hypertension was induced by partial ligation of the left renal artery. In mice expressing green fluorescent protein, laser-induced thrombosis was analyzed intravitally by using confocal microscope. Sodium nitrate (NaNO3) or sodium nitrite (NaNO2) was administered orally at a dose of 0.17 mmol/kg, twice per day for 3 days. Short-term nitrate treatment did not modify thrombus formation in either rats or mice, while nitrite administration led to pronounced antithrombotic activity. In hypertensive rats, nitrite treatment resulted in a significant decrease in thrombus weight (0.50 ± 0.08 mg vs. VEH 0.96 ± 0.09 mg; p < 0.01). In addition, nitrite inhibited ex vivo platelet aggregation and thromboxane B2 (TxB2) generation and prolonged prothrombin time. These effects were accompanied by significant increases in blood NOHb concentration and plasma nitrite concentration. In contrast, nitrate did not affect ex vivo platelet aggregation or prothrombin time and led to only slightly elevated nitrite plasma concentration. In mice, nitrate was also ineffective, while nitrite led to decreased platelet accumulation in the area of laser-induced endothelial injury. In conclusion, although nitrite induced profound NO-dependent antithrombotic effects in vivo, conversion of nitrates to nitrite in rats and mice over short-term 3-day treatment was not sufficient to elicit NO-dependent antiplatelet or antithrombotic effects.

Exercise capacity and cardiac hemodynamic response in female ApoE/LDLR(-/-) mice: a paradox of preserved V'O2max and exercise capacity despite coronary atherosclerosis.

We assessed exercise performance, coronary blood flow and cardiac reserve of female ApoE/LDLR(-/-) mice with advanced atherosclerosis compared with age-matched, wild-type C57BL6/J mice. Exercise capacity was assessed as whole body maximal oxygen consumption (V'O2max), maximum running velocity (vmax) and maximum distance (DISTmax) during treadmill exercise. Cardiac systolic and diastolic function in basal conditions and in response to dobutamine (mimicking exercise-induced cardiac stress) were assessed by Magnetic Resonance Imaging (MRI) in vivo. Function of coronary circulation was assessed in isolated perfused hearts. In female ApoE/LDLR(-/-) mice V'O2max, vmax and DISTmax were not impaired as compared with C57BL6/J mice. Cardiac function at rest and systolic and diastolic cardiac reserve were also preserved in female ApoE/LDLR(-/-) mice as evidenced by preserved fractional area change and similar fall in systolic and end diastolic area after dobutamine. Moreover, endothelium-dependent responses of coronary circulation induced by bradykinin (Bk) and acetylcholine (ACh) were preserved, while endothelium-independent responses induced by NO-donors were augmented in female ApoE/LDLR(-/-) mice. Basal COX-2-dependent production of 6-keto-PGF1α was increased. Concluding, we suggest that robust compensatory mechanisms in coronary circulation involving PGI2- and NO-pathways may efficiently counterbalance coronary atherosclerosis-induced impairment in V'O2max and exercise capacity.

A novel combined glucocorticoid-mineralocorticoid receptor selective modulator markedly prevents weight gain and fat mass expansion in mice fed a high-fat diet.

BACKGROUND: We have previously shown that antagonism of the mineralocorticoid receptor (MR) results in a potent antiadipogenic activity, in vitro and in vivo. Excessive glucocorticoid exposure is associated with obesity and related disorders in humans and mice. METHODS: In this study, responses to a novel combined glucocorticoid receptor (GR)/MR antagonist were investigated in a model of diet-induced obesity. Female 10-week-old C57BL/6J mice were fed with normal chow or a high-fat diet (HFD) for 9 weeks. Mice fed a HFD were concomitantly treated for 9 weeks with the GR antagonist mifepristone (80 mg kg(-1) per day) or the novel combined GR/MR antagonist CORT118335 (80 mg kg(-1) per day). Male, juvenile 6-week-old C57BL/6J mice fed HFD were treated with CORT118335 for 4 weeks. RESULTS: Mice fed a HFD showed a significant increase in total body weight and white fat mass, with impaired glucose tolerance and increased fat infiltration in livers. Interestingly, only CORT118335 completely prevented the HFD-induced weight gain and white fat deposition, whereas mifepristone showed no effect on body weight and modestly increased subcutaneous fat mass. Importantly, food intake was not affected by either treatment, and CORT118335 dramatically increased PGC-1α protein expression in adipose tissue, without any effect on UCP1. Both CORT118335 and mifepristone produced metabolic benefit, improving glucose tolerance, increasing adiponectin plasma levels, decreasing leptin and reducing mean adipocyte size. When tested in vitro, CORT118335 markedly reduced 3T3-L1 differentiation and reversed MR-mediated pro-adipogenic effects of aldosterone; differently, GR-mediated effects of dexamethasone were not antagonized by CORT118335, suggesting that it mostly acts as an antagonist of MR in cultured preadipocytes. CONCLUSIONS: Combined GR/MR pharmacological antagonism markedly reduced HFD-driven weight gain and fat mass expansion in mice through the increase in adipose PGC-1α, suggesting that both receptors represent strategic therapeutic targets to fight obesity. The effects of CORT118335 in adipocytes seem predominantly mediated by MR antagonism.

Endothelial glycocalyx integrity is preserved in young, healthy men during a single bout of strenuous physical exercise.

In the present study we aimed to evaluate whether oxidative stress and inflammation induced by strenuous exercise affect glycocalyx integrity and endothelial function. Twenty one young, untrained healthy men performed a maximal incremental cycling exercise - until exhaustion. Markers of glycocalyx shedding (syndecan-1, heparan sulfate and hyaluronic acid), endothelial status (nitric oxide and prostacyclin metabolites - nitrate, nitrite, 6-keto-prostaglandin F(1alpha)), oxidative stress (8-oxo-2'-deoxyguanosine) and antioxidant capacity (uric acid, non-enzymatic antioxidant capacity) as well as markers of inflammation (sVCAM-1 and sICAM-1) were analyzed in venous blood samples taken at rest and at the end of exercise. The applied strenuous exercise caused a 5-fold increase in plasma lactate and hypoxanthine concentrations (p<0.001), a fall in plasma uric acid concentration and non-enzymatic antioxidant capacity (p<10(-4)), accompanied by an increase (p=0.003) in sVCAM-1 concentration. Plasma 6-keto-prostaglandin F(1alpha) concentration increased (p=0.006) at exhaustion, while nitrate and nitrite concentrations were not affected. Surprisingly, no significant changes in serum syndecan-1 and heparan sulfate concentrations were observed. We have concluded, that a single bout of severe-intensity exercise is well accommodated by endothelium in young, healthy men as it neither results in evident glycocalyx disruption nor in the impairment of nitric oxide and prostacyclin production.

Role of xanthine oxidoreductase in the anti-thrombotic effects of nitrite in rats in vivo.

The mechanisms underlying nitrite-induced effects on thrombosis and hemostasis in vivo are not clear. The goal of the work described here was to investigate the role of xanthine oxidoreductase (XOR) in the anti-platelet and anti-thrombotic activities of nitrite in rats in vivo. Arterial thrombosis was induced electrically in rats with renovascular hypertension by partial ligation of the left renal artery. Sodium nitrite (NaNO2, 0.17 mmol/kg twice daily for 3 days, p.o) was administered with or without one of the XOR-inhibitors: allopurinol (ALLO) and febuxostat (FEB) (100 and 5 mg/kg, p.o., for 3 days). Nitrite treatment (0.17 mmol/kg), which was associated with a significant increase in NOHb, nitrite/nitrate plasma concentration, resulted in a substantial decrease in thrombus weight (TW) (0.48 ± 0.03 mg vs. vehicle [VEH] 0.88 ± 0.08 mg, p < 0.001) without a significant hypotensive effect. The anti-thrombotic effect of nitrite was partially reversed by FEB (TW = 0.63 ± 0.06 mg, p < 0.05 vs. nitrites), but not by ALLO (TW = 0.43 ± 0.02 mg). In turn, profound anti-platelet effect of nitrite measured ex vivo using collagen-induced whole-blood platelet aggregation (70.5 ± 7.1% vs. VEH 100 ± 4.5%, p < 0.05) and dynamic thromboxaneB2 generation was fully reversed by both XOR-inhibitors. In addition, nitrite decreased plasminogen activator inhibitor-1 concentration (0.47 ± 0.13 ng/ml vs. VEH 0.62 ± 0.04 ng/ml, p < 0.05) and FEB/ALLO reversed this effect. In vitro the anti-platelet effect of nitrite (1 mM) was reversed by FEB (0.1 mM) under hypoxia (0.5%O2) and normoxia (20%O2). Nitrite treatment had no effect on coagulation parameters. In conclusion, the nitrite-induced anti-platelet effect in rats in vivo is mediated by XOR, but XOR does not fully account for the anti-thrombotic effects of nitrite.

Skeletal Muscle Response to Endurance Training in IL-6-/- Mice.

We examined effects of moderate-intensity endurance training on muscle COX/CS activities and V'O2max in control WT and IL-6(-/-) mice. Animals were exercised for 10 weeks on treadmill for 1 h, 5 days a week at velocity of 6 m·min(-1) which was increased by 0.5 m·min(-1) every 2 weeks up to 8 m·min(-1) . Training triggered an increase of enzyme activities in soleus muscle of WT mice (COX: 480.3±8.9 U·g(-1) in sedentary group vs. 773.3±62.6 U·g(-1) in trained group, P<0.05 and CS: 374.0±6.0 U·g(-1) in sedentary group vs. 534.2±20.5 U·g(-1) in trained group, P<0.01, respectively) whereas no changes were observed in soleus of IL6(-/-) mice. Moreover, in mixed gastrocnemius muscle of trained IL-6(-/-) mice enzyme activities tended to be lower (COX: 410.7±48.4 U·g(-1) for sedentary vs. 277.0±36.5 U·g(-1) for trained group and CS: 343.8±24.6 U·g(-1) for sedentary vs. 251.7±27.1 U·g(-1) for trained group). No changes in V'O2max were observed in WT and IL-6(-/-) mice after training. Concluding, moderate-velocity endurance training-induced increase in COX and CS activities in muscles of WT mice only which suggests that IL-6 regulates training-induced skeletal muscle responses to exercise.