Glucocorticoids increase preproendothelin-1 expression in rat aorta

The effects of dexamethasone on post-asphyxial cerebral oxygenation in the preterm fetal sheep

Exposure to clinical doses of the glucocorticoid dexamethasone increases brain activity and causes seizures in normoxic preterm fetal sheep without causing brain injury. In contrast, the same treatment after asphyxia increased brain injury. We hypothesised that increased injury was in part mediated by a mismatch between oxygen demand and oxygen supply. In preterm fetal sheep at 0.7 gestation we measured cerebral oxygenation using near-infrared spectroscopy, electroencephalographic (EEG) activity, and carotid blood flow (CaBF) from 24 h before until 72 h after asphyxia induced by 25 min of umbilical cord occlusion. Ewes received dexamethasone intramuscularly (12 mg 3 ml(-1)) or saline 15 min after the end of asphyxia. Fetuses were studied for 3 days after occlusion. During the first 6 h of recovery after asphyxia, dexamethasone treatment was associated with a significantly greater fall in CaBF (P < 0.05), increased carotid vascular resistance (P < 0.001) and a greater fall in cerebral oxygenation as measured by the difference between oxygenated and deoxygenated haemoglobin (delta haemoglobin; P < 0.05). EEG activity was similarly suppressed in both groups. From 6 to 10 h onward, dexamethasone treatment was associated with a return of CaBF to saline control levels, increased EEG power (P < 0.005), greater epileptiform transient activity (P < 0.001), increased oxidised cytochrome oxidase (P < 0.05) and an attenuated increase in [delta haemoglobin] (P < 0.05). In conclusion, dexamethasone treatment after asphyxia is associated with greater hypoperfusion in the critical latent phase, leading to impaired intracerebral oxygenation that may exacerbate neural injury after asphyxia.

Interrelated modulation of endothelial function in Behcet's disease by clinical activity and corticosteroid treatment

Corticosteroids are commonly used in empirical treatment of Behçet's disease (BD), a systemic inflammatory condition associated with reversible endothelial dysfunction. In the present study we aimed to dissect the effects of clinical disease activity and chronic or short-term corticosteroid treatment on endothelial function in patients with BD. In a case-control, cross-sectional study, we assessed endothelial function by endothelium dependent flow mediated dilatation (FMD) at the brachial artery of 87 patients, who either were or were not receiving chronic corticosteroid treatment, and exhibiting variable clinical disease activity. Healthy individuals matched for age and sex served as controls. Endothelial function was also assessed in a prospective study of 11 patients before and after 7 days of treatment with prednisolone given at disease relapse (20 mg/day). In the cross-sectional component of the study, FMD was lower in patients than in control individuals (mean ± standard error: 4.1 ± 0.4% versus 5.7 ± 0.2%, P = 0.003), whereas there was a significant interaction between the effects of corticosteroids and disease activity on endothelial function (P = 0.014, two-factor analysis of variance). Among patients with inactive BD, those who were not treated with corticosteroids (n = 33) had FMD comparable to that in healthy control individuals, whereas those treated with corticosteroids (n = 15) had impaired endothelial function (P = 0.023 versus the respective control subgroup). In contrast, among patients with active BD, those who were not treated with corticosteroids (n = 20) had lower FMD than control individuals (P = 0.007), but in those who were receiving corticosteroids (n = 19) the FMD values were comparable to those in control individuals. Moreover, FMD was significantly improved after 7 days of prednisolone administration (3.7 ± 0.9% versus 7.6 ± 1.4%, P = 0.027). Taken together, these results imply that although corticosteroid treatment may impair endothelial function per se during the remission phase of the inflammatory process, it restores endothelial dysfunction during active BD by counteracting the harmful effects of relapsing inflammation.

Increased insulin-stimulated endothelin-1 release is a distinct vascular phenotype distinguishing Cushing's disease from metabolic syndrome

OBJECTIVE

Although much is known about the anti-inflammatory effects of an acute corticosteroid therapy, little is known about the effects on chronic hypercortisolism on endothelial dysfunction and proinflammatory alterations in patients with Cushing's disease (CD).

PATIENTS AND METHODS

We studied 9 patients with CD, 10 patients with metabolic syndrome and 27 normal controls. The tests consisted of an intravenous bolus of 0.1 U/kg insulin combined with a euglycaemic clamp technique with an arterialized forearm and assessment of the training parameters deep-venous balance of forearm glucose uptake (as an index of insulin sensitivity); NO(x) (nitric oxide end-products), c-GMP (second messenger of nitric oxide) and endothelin-1 release, as indices of endothelial function and proinflammatory systemic markers.

RESULTS

Forearm glucose uptake incremental area was significantly lower in Cushing's disease and in the metabolic syndrome than in controls, suggesting a state of severe insulin resistance. Compared to controls and to the metabolic syndrome, basal and insulin-stimulated NO(x) release incremental areas were significantly reduced in Cushing's disease, while forearm c-GMP release was similarly decreased in CD and metabolic syndrome. By contrast, endothelin-1 incremental areas after insulin bolus were significantly higher in CD than in controls and the metabolic syndrome, in the presence of increased TNF-alpha, IL-6 and CRP levels. Forearm glucose uptake incremental area significantly correlated with NO(x) incremental area, forearm c-GMP release incremental area, TNF-alpha levels and ET-1 incremental area.

CONCLUSIONS

In patients with CD, supraphysiological insulin levels are not able to overcome the insulin resistance due to chronic hypercortisolism. Furthermore, an increased proatherogenic risk profile is characterized by decreased nitric oxide synthesis and activity, enhanced endothelin-1 levels and increased proinflammatory markers.

Inhibition of Cortisol Production With Metyrapone Prevents Mental Stress-Induced Endothelial Dysfunction and Baroreflex Impairment

OBJECTIVES

This study was designed to investigate the role of cortisol in stress-induced endothelial dysfunction and impaired baroreflex sensitivity (BRS) by blocking cortisol production with metyrapone before subjecting healthy volunteers to mental stress.

BACKGROUND

Mental stress raises cortisol levels and is associated with increased coronary heart disease (CHD) morbidity and mortality, especially from sudden cardiac death. It also causes endothelial dysfunction and impaired BRS.

METHODS

We measured brachial artery flow-mediated dilation (FMD), a measure of endothelial function, and BRS in 36 subjects without CHD risk factors who were then randomized in a double-blind fashion to oral metyrapone 750 mg x 2 or placebo. Five hours later we subjected subjects to mental stress and then remeasured endothelial function and BRS.

RESULTS

Prestress cortisol levels were significantly higher in the placebo group at 270.5 (30.9) nmol/l versus 89.1 (11.8) nmol/l (p = 0.01), and the increase with stress was higher at 57.9 (17.9) nmol/l versus 11.2 (2.2) nmol/l (p < 0.001). In the placebo group, compared to baseline, FMD and BRS fell significantly from 4.5% (0.7%) to 1.4% (1.1%) (p = 0.02) and 21.4 (2.3) ms/mmHg to 16.3 (1.5) ms/mmHg (p = 0.04), respectively. In the metyrapone group, FMD and BRS were unchanged from baseline: 4.3% (0.9%) versus 5.1% (0.8%) (p = 0.48) and 26.4 (2.9) ms/mmHg versus 24.9 (2.6) ms/mmHg (p = 0.62), respectively. Analysis of covariation showed a significant effect of metyrapone on change in both FMD (p = 0.009) and BRS (p = 0.024).

CONCLUSIONS

Stress-related endothelial dysfunction and BRS impairment can be prevented by blocking cortisol production with metyrapone, demonstrating a direct or facilitative role for cortisol in these phenomena and suggesting mechanisms by which stress contributes to CHD and sudden cardiac death.

The Distinct Alterations Produced in Cardiovascular Functions by Prednisolone and Nitro-prednisolone (NCX-1015) in the Rat Highlight a Causal Role for Endothelin-1

Daily administration of prednisolone, but not the derivative NCX-1015 (or prednisolone 21-[4'-nitrooxymethyl]benzoate), to rats resulted in a time- and dose-dependent increase in mean arterial blood pressure (MABP), significant after 1 week for the dose of 6.9 micromol/kg i.p. (n = 10; P < 0.05), and 3 weeks for the lower dose of 1.38 micromol/kg. A similar dichotomy of behavior was observed with respect to myocardial contractility and renal vascular resistance, in either case augmented by 3-week treatment with prednisolone but not NCX-1015. In contrast, both NCX-1015 and prednisolone reduced plasma levels of corticosterone in a dose- (dose range of 0.69-6.9 micromol/kg i.p.) and time-dependent (1-3 weeks) manner. Similar profiles were obtained for plasma nitrate values, although they were increased selectively after NCX-1015 administration. In contrast, prednisolone, but not NCX-1015, augmented plasma endothelin 1 (ET-1) with a profile that mirrored the changes observed in MABP and renal blood flow. Supply in the drinking water of the ET-1 receptor type A (ETA) antagonist FR139317 [(R-2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]-carbonyl]amino-4-methylpentanoyl]-amino-3-(2-pyridil)propionic] or mixed ETA/B, but not of selective ETB, antagonists prevented the changes produced by a 21-day treatment with prednisolone. In conclusion, this study indicates 1) a lack of occurrence of cardiovascular alterations by nitro-releasing derivative of prednisolone (NCX-1015), and 2) a functional link between prednisolone effects and the endogenous endothelin-1 system.

Evidence for microvascular dysfunction after prenatal dexamethasone at 0.7, 0.75, and 0.8 gestation in sheep

Dexamethasone (DM) was administered to pregnant ewes as three weekly courses of four injections of 2 mg at 12-h intervals. DM (n = 7) or saline (n = 7) was given starting at 103 days of gestation (dGA; term approximately 149 days). Fetal femoral arteries (approximately 300-microm internal diameter) were evaluated using wire myography at 119 dGA. DM-exposed fetuses were significantly smaller than saline-exposed fetuses. DM exposure increased maximal contraction to 125 mM KCl, and maximum tension developed along with sensitivity to endothelin-1 and relaxation to bradykinin. Preincubation with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester shifted the dose-response curves to endothelin-1 and acetylcholine to the right in controls but not in the DM-exposed group. Relaxation to acetylcholine and to the nitric oxide donor sodium nitroprusside was similar in both groups. The combination of enhanced endothelin-induced vasoconstriction, abnormal endothelium-dependent relaxation, and normal endothelium-independent relaxation indicates microvessel dysfunction following antenatal DM administration. Because such dysfunction is associated with several forms of adult hypertension, our results indicate the potential for consequences of antenatal glucocorticoid exposure on adult cardiovascular health.